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How Do I Reformat My Machine If I Don’t Have a Windows CD?


I want to format my laptop. It has Windows XP with service pack 2 installed. I don’t recall getting a Windows CD, so first how do I format and second can I do it without that setup CD?

The answer for most people is simple: no, you cannot. In fact, you should not if you don’t have the Windows setup CD.

Yes, yes, it can be done without the setup CD, but I’m guessing you won’t like what you end up with. Not at all.

Let’s be clear on exactly what it means to “reformat” a machine.

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Let’s be really, really clear.

Reformatting a machine begins by erasing everything on it.

Got that? Everything. The operating system, all your programs, and all your data. Everything. Gone.

I’m sorry if that seems obvious to many of you, but trust me it’s not at all obvious to many others.

So before we even get to step 1, “step 0” is to make sure that reformatting is exactly what you want to do. That means that either you’ve backed up everything you need to save off of the machine, or that you’re ready to reload the machine, or you really do want an unbootable empty hard drive.

When most people talk about “reformatting” a machine, they really mean “reformat and reinstall”. It’s a two step process. Step 1 is simple, step 2 typically takes a long time.

Step 1: Reformat

Formatting a disk is a process that simply prepares it for use by writing what is effectively “blank data” to the entire disk. The result is that the disk is ready for use. Empty, but ready for use.

“Re”-formatting a disk is simply repeating that process on a disk that was already formatted. It can be a relatively quick way to erase the contents of the disk to start over, or to write to the entire disk to locate and compensate for any physical defects on the media.

As you can see, a reformat and reinstall is an extreme step.

My recommended approach to reformatting a hard disk for most people is to boot from your Windows install CD, and indicate that you want a new, clean install. I recently did exactly this on my old laptop, and went so far as to use the partition manager that is part of Windows setup to delete all the partitions on the laptop’s hard drive and create a new partition that encompassed the entire disk. Windows Setup’s next step was to perform a full format of the hard drive before it continued.

If you don’t have a Windows install CD, there are still approaches to get the reformat done. You could boot from one of the many Linux Live CDs and use the tools therein, or boot from some of the boot disks available at In the later case you should be able to use the familiar “Format” command directly; since you didn’t boot from the hard drive it won’t be “in use” when you run the command.

After reformatting you’ll have an empty hard disk. Which then brings us to our next step:

Step 2: Reinstall

This is where not having your Windows install CD really hurts. Without a disk to reinstall from, you can’t reinstall! Your only options are to install a different operating system (such as one of the free Linux’s) or turn your machine off.

Or purchase a Windows CD. (If Windows came preinstalled, you might check with your vendor for a CD – it’s unlikely that they’ll give you one, but perhaps they’ll have a discount or other solution for you.)

One lesson here is to always get a copy of Windows on CD when you purchase a machine with Windows preinstalled.

Assuming you have the Windows CD, the remaining steps are simple to describe, but time-consuming to actually perform:

  • Reinstall Windows. If you used Windows setup to reformat your machine as described above you’re already on your way.
  • Reinstall and reconfigure all the applications you use. I’ve focussed on having the Windows CD, but the same actually applies to the setup CDs for any software on your machine. Make sure you have them or can download the applications in order to reinstall them at this point. All of them.
  • Reinstall your data or other customizations. You did backup your data, right? This is where you copy that data back to your freshly reformatted machine.

That’s all there is to it.

As I said, I did it recently, and it took about a half day to get my laptop reformatted and then up and running again with a fresh and fully up-to-date Windows, updated drivers, security software, and some of the basic applications I want for its new intended purpose. A full reformat and reinstall of my “primary” machine typically takes most of a day to get to basic functionality, and then I find myself installing missing applications off and on for days.

As you can see, a reformat and reinstall is an extreme step. Make sure you really want to do it before you take the plunge.

An Alternative: A “Non-Destructive” Format

As I mentioned, one of the functions of a full format of a hard drive is to write to the entire hard disk and identify and possibly compensate for bad sectors or areas on the hard drive that have errors. What’s called “low-level” formatting does this quite literally by writing data to the disk and trapping any areas on the disk for which the writes fail. The side effect, of course, is that any data that was there previously is overwritten and lost and you end up with a blank hard disk.

If you’re reformatting in order to deal with possible errors on your hard disk, there is another approach: SpinRite.

SpinRite is a data recovery tool that, in a sense, performs a non-destructive low-level format of the hard disk. It reads the existing data from the drive, performs its write tests and “formatting”, and then replaces the data. When SpinRite is done, everything on your hard drive is as it was when you started except that bad sectors have been identified and removed from use, and quite often the drive appears to run faster.

SpinRite is called a “data recovery tool” because if you have bad sectors on your hard drive, it’ll do everything in it’s power to recover the data before performing its other operations. The net result is that data thought lost to hard disk errors can frequently be recovered as the drive is processed by SpinRite.

SpinRite is not free, but if you’re facing data loss it could easily be a bargain.

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30 comments on “How Do I Reformat My Machine If I Don’t Have a Windows CD?”

  1. One caveat to what you’ve said – many computer vendors today are not including a copy of the OS on a CD by default when you buy a computer today – instead they have a “hidden” partition on the drive with a disk image. When you want to “reformat and reinstall” you just run the recovery disk (comes under different names, depending on the company) which writes the disk image over your current hard drive contents, effectively restoring your computer to the day you got it. As with your comments, this still does erase all data and drive contents, so should not be done unless you’ve backed up first.

    Advanced users sometimes do this exact same thing but with a disk image utility (Norton Ghost, e.g.) after they’ve got their computer set up with all the applications the way they like it. Then, next time they feel a need to reformat and reinstall, all they have to do is use the disk image utility to copy the disk image over and their system is back to the way it was the day they made the image…including all software applications and windows customization settings they made before the image.

  2. Hi, thanks for posting this, let’s say you had a very expensive alienware desktop and it starting having problems. I’m a procrastinator so I usually deal with some major problems with my comps. Anyways it finally got to the point where I couldn’t even use this computer it wouldn’t even start up. I wanted to reformat+reinstall A year ago but when I tried with the WINDOWS XP cd … when it came to entering the registry key I couldn’t because my house keeper threw it away.

    So that leads me to where I am now, a year or more later….. don’t know where the XP cd is. I did download a program just now that finds out ur Registry Key. So… now I have that but no CD.. I’m going to take your advice call alienware ask them for the windows xp cd or the restore one.

    Any words of advice for me? I didn’t turn this computer on in over a year till 2 days ago and it worked but got the same blue screen errors and all of that stuff. I got rid of an lsass.exe error by reading someones posts. But my computer is still majorly messed up and i’m 100% i need to reformat+reinstall XP.

  3. No original CD but key number is known via sticker on machine,

    Can a friends copy of XP be used for the re installatiion using my key. ?

  4. quote>>Advanced users sometimes do this exact same thing but with a disk image utility (Norton Ghost, e.g.) after they’ve got their computer set up with all the applications the way they like it. Then, next time they feel a need to reformat and reinstall, all they have to do is use the disk image utility to copy the disk image over and their system is back to the way it was the day they made the image…including all software applications and windows customization settings they made before the image.

  5. Go to My Comuter > Drive C > look for a folder named 1386. Open it and look for a file called wnnt32.exe. This is the Windows installation file. It will wipe your computer of everything and reinstall Windows.

  6. Leo HELP! I am not all that computer savy for starters.Okay I was given a laptop with business windows or something on it.I am sure they wiped it clean before they gave it to me.But I cant get past the first screen because it wants a password.What do I do ? I dont have the password or a disk or anything.Its just an old laptop not real old though still usuable that I got for free.

    Assuming you don’t want anything currently on that machine, just get a copy of Windows and install it from scratch.

    – Leo
  7. Hello Leo. Thanks so much for info you put on site. I have a friend that has a pc with an illegal copy of windows xp on it and I unknowly went to update and then it didnt pass the validation tool so is now froze. I do have a legal copy of xp to install but I’m not sure how to get it to function outside of a hard reboot with windows cd in drive. Any suggestions very much appreciated. Pat

  8. Hi Leo. If I reinstall window XP, does it also reformat the hard drive at the same time? If so, I don’t have to reformat the hard drive first and then reinstall window XP. Am I correct?

    You should be given the option to reformat as part of the installation process.

    – Leo
  9. I am trying to install Window XP and it is setting it up, my product key number on the package is not taking. I install up to 39 minutes of my cd, then I reboot it again and it comes up with installing the product key which is not taking it on the package. Is there a way I can install Windows without the product key numbers and part of the window is display? I can not get to My Computer, just the setup window. Please help

  10. Hello Leo! I recently reformatted and reinstalled Windows XP on my laptop. However, upon getting it back up and running and on the Internet, I noticed that my hard drive is almost full. There’s no sign of anything still on the hard drive, and it has a capacity of 60 GB and almost all of it is being used. Did I miss something? Thanks.

  11. Leo,I have a HP Presario SR1215CL that a friend gave me, it has many problens and conflicts, this computer was purchased in 2005 it was never updated and the Norton trial was never activated, there are locking problems as the administrator never fixed, this computer has many programs that were never used and a lot of junk files, I have my own windows XP operating Disk, should I reinstall using my disk and will this fix most problems,I did download AVG and cleaned up about 70 trojans and other viris that were present. Thanks,
    Gerald Becker

  12. hi sir leo how can i fix my hp 110 mini laptop it is stuck on the desktop reboot it..i am able to move the cursor but it is not functioning.

  13. I want to format my laptop that have windon vista to window xp or window 7. My laptop model is HP compaq NC6220. Processor 0.98GB, HD 40GB. The cd/dvd drive is fault but it only recognised dvd drive software installations pack but cd it would not. Can i cope the window software into a flash drive then used it to format the system. Ple advice me on it because the window vista is giving a lot of problem.
    Ple send me reply on: [email address removed]
    Thanks hoping to hear from u.

  14. Hello Leo and thanks for a great article, however it did not address my needs. The problem I have is that I wanted to perform a clean install of Windows 7, upgrading from my Vista. So I use the custom install option as I should, but after having gone through the installation process, it comes to my awareness that somehow, this custom install in fact SPLIT MY HARD DRIVE SPACE TO HALF THE ACTUAL CAPACITY. I assumed that this custom install would format my hard drive, but as seems to be the case instead, is that it must have created enough space on the hard drive to perform a quick format instead. I am therefore trying to find a way to properly format the hard drive, as I do not believe the hard drive itself is damaged or corrupt, merely that Windows 7 used half of the hard drive space to dump information from Vista. So what I did was that I of course tried to run the set up program again, believing that Win 7 merely created a faulty partition I did not notice and deleting this partition would solve my problem, but when prompted where I want to install Win 7, it turns out that the limit of my hard drive remains the same. Win 7 does not recognize the rest of my hard drive capacity, and I am at loss as to why.

    I tried to run the SpinRite program because it seems to be what I were after, but as with all other programs I’ve unfortunately encountered, it will not function as bootable from a CD. I burned the .iso file but it just says that there is no proper media drive in my CD drive. Yes, I have set my motherboard to boot from CD since I had to do this to install WIn 7 in the first place.

    Does this problem with my hard drive relate to what Win 7 calls Windows.old? What I noticed after my first install was that it indeed was not a clean install at all, as I in fact had several folders lying around that were left from Vista, yet other information such as installed programs were lost.

    I would love to hear your response to this problem.

  15. Hi Leo, I have bought a new lap top with Windows 7 installed so I have promised a friend my desktop, so I wish to format the hard drive, before I give him it. I will then reinstall as I have a Vista installation disc. As I am a pensioner and I hear people saying to reboot from disc, the problem is I do not know how to do it, as I only have a basic knowledge in computing. Thank you.

  16. Leo, Why would one need to reformat a HD anyway — unless it had stopped functioning?

    A true reformat is a useful way to erase everything as well as “touch” every sector on the hard drive refreshing the magnetic image of the data.

  17. Hi Leo can u please tell me since i ve problem installing window 7 in my HP Compaq nc6220 which tells me during the installion that i need cd/dvd driver which i didn’t know where i find even hp home

    thanks in Advance

    • The article you are commenting on has your options for that. Also check out the other article listed under “Read more” and you’ll find all your options.

  18. Hi leo!
    I have perhaps a different type of problem than others. I have installed Windows 8.1 on one partition of my hard disk and windows xp sp3 on another. Xp got too much slow so i tried to remove it by formatting but am not able because i don’t have a c.d of both windows. So i tried to format the xp installed partition through win 8 log in but it shows Windows can’t format the drive. Then i deleted all the folders of xp drive but one didn’t delete due to unknown reasons, now when i start PC and choose win xp it doesn’t load and says .dll and sys32 file missing. Now please guide me how do i delete/format the win xp partition drive from win 8 log in. Please help so that i can make my computer faster, safer by removing XP. Thanks!!!

  19. i have formatted my laptop…and istalled new os….badly i forgot to copy my important (photos) from old drives…now is there any possibility to get them back….

  20. Hi Leo,I have a problem with my laptop which is demanding for an administrator password. I have removed the Simus battery yet it’s still the same. What can I do to by pass or format it?

    • If you boot from an install CD you won’t need an administrator password. If it’s asking for a password before it boots from anything at all, that’s a BIOS password, and you may not be able to reset it – you’d have to check with the computer manufacturer.

  21. Can anyone give me a website for a step by step guide to reformatting a Compaq Computer.
    I dont however have the install cd but the tower has the product key stuck to the side.
    What does this mean?
    Thank You.

  22. my laptop D6400
    when I put it on my laptop on it will come on and stand still showing the windows on the screen

    what should I do please

  23. By mistake, I delete one file from c drive and from that time when I switched on my laptop it will give notification as bootmgr is missing

    What should I do!!?

  24. Hi, Leo!

    No offense intended….but at the top of the article where it says, “I want to format my laptop. It has Windows SP with service pack 2 installed.”……..I think someone meant to type Windows XP!



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