have you tryed booting up the system with the damaged disk attached only? if so was it recognised in the bios! if so then maybe you have an electrical problem with the circuitry on the hard drive.if however it was recognised and didn't start possibly due to a virus, have you tryed booting up the bootdisk and from prompt writing or copying a new partition table to the hardisk with FDISK /MBR , did that not work?

if it did but you can't see the files that where originally on the harddisk try a file scavenger program, something similar to that of lost and found.

thats all as i ever do,

1) Isn't recognised in the Bios (damaged circuit board) change it for an identical
working one and recover your files then loose the disk.

2) if its a bootsector virus, (copy a new bootsector from a floppy) FDISK /mbr

3) if it the data that can't be found then run a file scavenger program can be a
time consuming job, but you'll get there eventually.

Works everytime for me well unless its down to the disk being off its bearings then it's off to the lab.