Originally Posted by Freebase Dali

In the bios, if you do not see the hard drive listed, the drive is either dead or not connected. If you do, it's possible that the partition table or master boot record on the drive is corrupted.
If you don't see the drive listed, reseat the hard drive and try to boot. If you do see it listed, assuming that the file system is not corrupt on the hard drive, you can connect it to another computer and access it like you would a secondary drive, and salvage any data, then wipe the drive and reinstall an operating system on it.
Also, you can download a program called MsDart or ERD Commander, (not free, but you can get it pretty easily or use a trial version with a 30 day limit) as a .iso, and burn it to a cd (as a bootable cd) and inside the program after you boot to it, there's an option for Disk Management that will let you mount the hard drive and explore it.
If the drive is unmountable, there is a problem with the MBR or partition table. If that is the case, you may still be able to retrieve the data by choosing not to mount the drive but exploring it anyway. If the file system is intact, you will be able to browse the contents and back up any data straight to an external drive.
If you can't even explore the contents of the disk, you're likely not going to be able to retrieve any data, and should just wipe the drive, format it with NTFS, and see if you can access it normally on another computer. If so, then that's your option.
If you can't format it/doesn't show up in Disc Management in Windows, the drive is dead and will serve the rest of its purpose as a paperweight.

Good luck.