I’m certain there’s a limit, but I have no idea what it is. I’m also certain it’s not the problem here.
You attach a drive, either internal or external — perhaps even get the “new drive attached” sound — and then … nothing. Nothing corresponding to the drive appears in Windows File Explorer.
There are a variety of reasons this might happen. I’ll show you how to deal with the most common scenario.
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A disk can sometimes be connected and not have a drive letter assigned to it. When this happens, the hard drive will not show in Windows File Explorer, even though it’s otherwise working. Use Windows Disk Management to assign a drive letter manually by right-clicking on the drive, selecting “Change Drive Letter and Paths…”, and clicking on “Add…”.
Disk Management
We’ll start with your problematic disk disconnected. Physically unplug it from your computer. (If this is an internal disk, it’ll have to stay connected. We’ll deal with that below.)
In Windows 10, right-click on the Start button and click on Disk Management. (In prior versions of Windows, right-click on “Computer” or “My Computer” on your desktop or in the Start menu, click on Manage, and in the resulting Computer Management window, click on Disk Management.)
The Disk Management utility shows you all connected disks, memory card readers (which may or may not have cards inserted), and optical drives (which may or may not have discs inserted). The top pane lists all partitions on all disks, and the lower pane lists all disks with the partitions they contain displayed in boxes alongside.
Now plug in the disk you want to access.
If a new entry appears in Disk Management’s lower pane, that’s very good news. That implies the hardware is working and the drive is being recognized by Windows.
Internal and already-connected drives
For internal disks (or disks that for whatever reason can’t be unplugged and plugged in again), we have to hunt a little.
In Disk Management, see if there is a disk listed that matches what you know about the disk you’re trying to access. That could be the name of a partition on it, or more commonly, the size of the disk as compared to the other disks on your system. For example, if you know you have a 1TB disk that’s working and a 16GB disk that’s not, if you find a 16GB disk listed, you can be fairly certain that this is the disk we want.
If the disk does not appear at all when you plug it in, or if you cannot find it listed based on its characteristics, then you’re likely looking at a hardware problem. Check the cables and connections. If this is an external disk, see if it’ll work on a different computer.
The more common case, though, is that the disk appears in Disk Management but still doesn’t appear in Windows File Explorer.
Disks that appear, and yet don’t
Let’s widen the first column of information in the upper pane listing the drives in my example, and look closely. Notice something interesting?
While my primary disk’s single partition is listed with drive letter “C:”, and one of my external disk’s partition is listed with drive letter “D:”, there are a couple of drives there that have no letter at all.
“G-UTILITIES” is a partition on my (working) external drive.
This is extremely common, and not related to our problem at all. Many disks come with multiple partitions; some contain utility or recovery tools. In this case, the clue is that my external hard disk is a G-Drive branded disk, and the “G-UTILITIES” partition is likely to be utilities that came with the drive. It’s a small partition, and I didn’t bother to take the time to remove it.1
The more problematic disk is the one named “NOTEN15GB”.
The name comes from the label of the single partition on the disk that is 15GB in size. That’s my 16GB thumb drive (and yes, drives labelled 16GB may show as 15GB because of the way disk space numbers can be (mis)used. I talk about why that is here.)
Yet it has no drive letter, and as a result, does not appear in Windows File Explorer.
While I don’t have a specific reason2, I believe this to be the common cause for a large number of “functioning properly” but still inaccessible disks. It’s been successfully attached to the system, but for one reason or another, a letter hasn’t been assigned.
It’s an easy fix.
Assign a drive letter manually
Right-click on the drive in question in either the top or lower pane (lower pane shown).
Click on Change Drive Letter and Paths…
As you can see, the drive can’t be accessed because the list of the ways to access it is empty.
Click on Add….
Ignore the “Mount” option; we’re just going to assign a drive letter. As you can see, Windows defaults to the first available drive letter, which on my system is “E:”. There’s a dropdown list, though, and if you’d like the drive letter to be something else, you can select a different letter.
Click OK.
Disk management updates its display to reflect the letter assigned to the disk.
And in Windows Explorer, we can now see the drive.
While this doesn’t cover every case of a connected drive not appearing, in my experience this is a common enough occurrence that it may well cover your situation.
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In Windows 7 can I assign drive letters (temporarily) to the recovery partition and the “SYSTEM RESERVED” partition so I can see what’s there, or will doing so make my PC unbootable?
04-Sep-2010
Uhm, yes, well — just be sure to remove that new drive letter again after you’re done exploring. You really don’t want to risk Windows becoming confused and failing to recognize that (possibly essential) drive or partition, due to the added drive letter!
Even better still — you know thus is coming, don’t you? — do a full backup before making any changes at all… Justin Cayce. :) :) :)
EDIT: Right-clicking on the nameless recovery partition yields nothing but a link to Help, which of course offers no help. So the answer to the first half of my question is no, I reckon.
I have run into a similar problem often.
On Windows XP systems if a drive letter near the beginning of the alphabet, say E, is assigned to a network drive, a bug in XP causes it to get confused with newly inserted USB devices. If E would be assigned to the USB device had there been no network share, you end up not seeing the USB device. Change the USB device to F or G or H, as Leo described, and all is well.
That XP has this bug for so so long, says a lot about Microsoft.
I had a similar problem with my HP laptop. The CD/dvd drive “disappeared”. I did some research (using Google of course)and discovered that this was not an isolated problem. The solution was to make a change in the registry. Once that was done,the drive “reappeared” — only to disappear once more later on. More research and a second edit to the registry to keep the first one from being changed again. Some software I had was doing it. I’m sorry I can’t be more specific but I’m writing this at work and don’t remember the exact changes required.
to all,
PLEASE read this, for this issue.
I can detail this much more than here, I was researching this problem for over TWENTY hours !!
AFTER numerous google searches, I came across this reference to
Diskpart
Automount
and a registry key
to ALL of you, who havethis problem; LOOK at thisk ad if this DOES prove to be the majority’s problem, there SHOULD be a thread of this sent to google, to be triggered to come to the top of searches of
“usb drive is not assigned a drive letter”
The gentleman’s name at the bottom of this thread is part of the thread which I captured, KUDO’s to him !
Nick spagnola
Leo, any response to this to my mail, is appreciated, for further diagnosis, as it drove me NUTS !!!
We can verify the status of Automatic mounting of new volumes by
looking at the value of the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MountMgr\NoAutoMount
If the value is set to 1: This indicates that Automatic mounting of new
volumes is Disabled.
If the value is set to 0: This indicates that Automatic mounting of new
volumes is Enabled.
Hope it helps.
David Shen
I have an external disk which used to work perfectly with Windows XP Pro via a USB connection. However, now when I connect it through USB I receive the following message:
ATA/ATAPI Bridge
and Windows XP tries to install some kind of driver, which it cannot find! As a result this entire external drive with all the data on it has become inaccessible. Do you have any recommendation as to connecting and salvaging this external drive?
Thanks for yet another helpful article. There may sometimes be a very simple explanation – I had this problem a few years ago and finally discovered that in an XP tweak app or it may have been a Symantec utility that I’d INSTRUCTED the program what drives to show, and because I had no need of drives H to Z showing in various lists I’d hidden them. By the time I got to use drive letters H,I, J etc I’d forgotten about the original instruction. It was a very easy fix – just one of the dangers of fiddling unnecessarily however :o)
I had this problem quite a while ago on a Pavilion running XP and several USB external drives. HP support recommended a BIOS upgrade and this fixed the matter.
I tried to assign a letter to the hard drive and it would not let me as it was grayed out. So a friend suggested that I use a tool called MiniTool partition Wizard home version. I was able to put a letter to the drive using that software, but when I went back to the main screen it was still blank, well it did have a “Star:” and I was still unable to access the drive, but looking closely at the software I saw they has another program called the MiniTool PowerData Recovery 6.6. I installed that and was able to copy to files to my other hard drive. Software was free to home users, but the date recovery was limited to 1 gig.
You might want to take a look at the software and see how useful it is. Thanks for answering back, I read all of your articals.
nicholas spagnola comment was bang on!
Just modify the registry to the proper value of 0. When I navigated to the key my value was set to 1 which indicates the automatic drive assignment was disabled. I now changed my value in the registry to 0 and voila! The problem was fixed. THANKS VERY MUCH for posting this Mr. Spagnola. Was frustrating to find the answer.
In Computer Management, my external HD shows a red downward arrow when plugged in and it has thee designation “Disk 1 Unknown Not Initialized”. When I right-click it, I get these 3 options: “Initialize Disk – Offline – Properties”. The second option results into “The request failed due to a fatal hardware error”. Does this mean I can never recover its content? If I open Properties, under the Event tab I see – among other entries – one labelled “Device not migrated” which gives me pause.
Any tips?
Hopefully you have that data backed up somewhere. There is, indeed, a possibility that there’s a fatal hardware problem.
I would first try the drive in another computer. Also try a different USB port and cable. DO NOT INITIALIZE the disk — that will most certainly erase whatever is on it.
So, “initialize” and “format” are synonyms?
(I’m very glad that wasn’t the case for my old Commodore-128 computer and 1571 disk drive! On the C128/2571, “initialize” and “format” are two very distinct commands; to make them synonymous would have resulted in utter disaster.)
Not really. To be honest I’m not 100% convinced I “get” just what initialize is. I believe it’s setting up data structures for partition management (MBR or GPT), and the format is what you do to individual partitions.
Whenever I’ve had an ssd connected via usb and it didn’t show on W7 Explorer, I discovered that the sdd was listed in Device Manager as being “offline”. The ssd was supposedly “in collision” with another drive, whatever that means. I don’t recall how to bring a drive back on line, but doing so revealed the drive to W7 Explorer. Perhaps Leo will refresh my memory.
Assigning it a drive letter in Disk Management should bring it “online”.
I am wondering Leo if I can buy any of your books in hardcopy? if not I need to get the electronic versions to read from my computer and I need to know how to keep the books on and accessible on my laptop. I’m not afraid to spend some money for a few of your books so help me with this. thank you, BRUCE W HARTLEY. {personal information removed}
You can get hard copies of Leo’s books from Amazon.
https://www.amazon.com/s?k=Leo+Notenboom&ref=nb_sb_noss
Purchasing a hard copy also gives you a login to be able to also get the electronic copies. If you lose the copy on your computer, you can log in and retrieve it again. If you forget your login, it’s also retrievable.
Mark’s given you the link to the books on Amazon, but I also have to point out: if you’re afraid of losing anything on your computer then YOU’RE NOT BACKED UP.
Please start backing up as soon as possible. You could lose things more important than my books.