I was playing WoW when my computer crashed (everything froze) so I left it for a few minutes before turning it off with the power button. When I turned it bback on I found my WoW shortcut had turned iconless and my D: drive had completely dissapeared from 'Computer'. So it looks like the drive is dead, anyone got any ideas what happened?
You said it in your post - your drive may have in fact died.
Open up the case and ensure all your cables are snug. Try again.
If nothing, plug the HDD into a different sata port and see if it is recognized.
If nothing, go into the bios and see if it is recognized there.
Also you may want to run a data recovery program such as Recuva. Assuming the drive is powering on and recognized by the BIOS Recuva should be able to access it. Worst case scenario it doesn't retrieve anything, best case scenario you get your drive in a state that you can at least recover some items. Expect to replace the drive though, sudden partition loss is a sign of a dead drive.
As a side note I use GetDataBack NTFS, Recuva, and Undelete for data recovery programs.