Ultimately, a drive can fail in so many ways that it’s not at all surprising that you didn’t get any warning – other than the failure itself.
It sounds like you’re expecting symptoms associated with a failure. While some do have signs (and I’ll go through a few that indicate that your hard drive is failing), you don’t ever want to rely on these absolutely.
Some common failure symptoms
Surface defects can accumulate over time. You may end up getting warnings or CRC errors from the operating system as it has trouble reading specific areas of the disk.
The hardware itself could slowly fail. Things like the grinding that you’ve experienced in the past could be the result. The problem is that some slow failures could also be very, very silent. They could result in only poor performance or overheating.
Some failures could be sudden. The circuit board might fail abruptly. Or there could be a physical disaster to the disk.
Think about it: you’ve got metal platters that are spinning at up to 10000 rpm. That’s fast!
And the little pieces of hardware that are flying over the disks to read the information are really small. If something gets loose suddenly and it starts flying around inside the disk, that could cause massive, irrecoverable damage.
What you do need to realize
Disk failures happen. That’s something that I think everybody really needs to realize. Perhaps more importantly there is simply no guarantee of a warning.
Sometimes, it can be slow. You may get some warning or they could be completely instantaneous as you’ve experienced here. The only way to be prepared for something like this is to back up.
A two-week old backup is great, but as you’ve noted, it would have been nice to have something more recent. That’s why I often recommend daily backups if the computer has any kind of important or heavy use.