If you have any non-standard drive connected, it might just be taking a drive letter that is already in use. It's a massive problem in WindowsXP, plug in a USB pendrive and a networked drive get's kicked out.
If you can see it in Computer Manager but not in Explorer, then that's the first thing I'd check - right click and select Change Drive Letter. If it's missing from Computer Manager, then you should hope that it's just the cables... properly restoring corrupt files is a massive/expensive/troublesome gamble. If you suspect that the drive is dead, make sure you try it in a different PC, it might survive long enough for you to get your files off.

I am the one who knocks...
