I use a hard drive which I took from my old compaq notebook as an external storage device. The problem is that it is no longer showing up in 'my computer' when it is connected, and I have a lot of important files on it. Is there a way to recover them? There were no symptoms, it was working, then suddenly it was not. I took it to another computer to copy some files to it, so I don't know if it suffered ant shock being carried in my knapsack.
Not that anything is a guarantee with a troublesome hdd but just because your computer cannot see it doesn't mean that it is bad. There are a few places that you can check to see if your hdd is still being recognized by your computer.
First is obviously the "my computer" icon on your desktop. Make sure that it did not just get a different letter assignment because its "normal" drive letter is already taken.
Next is only if you have any computer monitoring software. I have open hardware monitor (same as hwmonitor but better). It is obviously used more for monitoring temps and CPU action but if you have a monitor like this and your hdd showed up before, you should check to see if it is still there.
The last windows location to look in is the computer management section under storage. Find the tab that says "Disk Management". If you can see it there and don't know what to do with it. Then write down and repost what all of the information in the columns next to your drive say.
If you cannot see your hdd in any of those places then you need to verify that it can be read at all. You need to check in your CMOS and see if you BIOS is recognizing the drive. This could be a little tricky because if you have an older motherboard then your BIOS may or may not recognized an external drive before boot. But if you have any kind of recent BIOS version you should be fine and BIOS should be able to see your external drive.
Now we hit a fork in the road:
If you can see your drive in CMOS then you should try and get your hands on a bootable cd that has a partition manager on it (something like UBCD). If you can do this you can run a multitude of tests on your HDD to see what exactly is causing it not to be recognized in windows.
If you cannot see your drive in CMOS then you should try bringing your drive to a friends computer and seeing if it will connect there. If you can't find a computer that your drive can connect to then I am afraid you have a dead HDD.
***A word of advice, if you haven't already (you really should have), you should be ready to make a backup of the information on the HDD the second that you get any kind of connectivity from the drive.
Sorry about the long post, post back with any new information or questions and good luck.