Western Digital drive not showing up in My Computer

[gobbog]

I have windows XP service pack 3 and my 1tb western digital hard drive is no longer showing up. I have had the drive for over a year and it was working fine until the other day when i plugged it in and the drive didnt show up in my computer. It shows up under device management but not under disc management so i can't assign it a letter. I have tried Easeus but it wont run on the drive.
Also i cannot start my computer with the drive plugged in, it gets to the boot screen and makes a click and restarts

 

[mailpup]

It's not completely clear if this is an external drive since an internal drive can be "plugged in" too so to speak. Anyway, let's presume it's an external drive. I'd say either the enclosure has failed or the hard drive itself has.

 

[Leeky]

As above, sounds to me like an external drive and either the enclosure has failed, or the drive has.

You can test which one has by removing the case sides, and then fitting the hard disk inside a PC. If its recognised by the PC and runs fine, the enclosure is at fault. If it doesn't work at all, the hard disk is at fault.