Does bios see the hard disk. When plugged in ?
If not nothing you can do to recover files
If it is seen by bios then WD has diagnostic software which can run on floppy disk or cd.
This can report on problem
Do not use disk part or make any changes to drive
Until you have evidence the hard disk has no physical faults and problem is corruption of something like MBR / partition data boot sector or boot.ini problems
Which can be fixed