Hard Drive Failure... What Happen?

What would cause a hard drive to suddenly loose everything on the drive? Prior to the hard drive loosing all content, the hard drive had about 5 gigs of photos on the hard drive. The hard drive was formatted to NTFS but now reads RAW with 0 bytes used, 0 bytes free space, and capacity 0. I get a message that says, Drive is not formatted, do you want to format the drive?

How can a drive revert back to RAW condition? There was another hard drive that contains the operating system thats AOK. I was downloading updates from Microsoft when the computer froze up and I had to do a reset. After the reset the computer showed that there was no operating system. I then disconnected the D hard drive from the ribbon cable and the computer booted AOK. Both C and D hard drives were on IDE cable 1 with the D drive as the slave.

What the hell happen?

A few things come to mind...head crashing on the disk, screwy FATs, and motor failure, right off the top of my head. Do you hear any clicking noises, or any other unusual sounds?

Get an app called killdisk (google it, its not hard to find), boot into DOS, and run the app (it goes on a floppy). That usually solves weird stuff like this. Of course, it also erases everything on the disk, so keep that in mind. You might want to try some recovery software first to get your pics and stuff off the drive.