Why is it "dead" - what happens when you boot the computer?
Seagate Barracuda series 7200.11 hard-drives had a firmware issue which causes
the hard-drive to stop booting. It no longer appears in the Bios. But it is not dead.
When you listen to it, it is still turning, and makes all the normal sounds. So if that
is the case, you can send it to Seagate and they will fix it for you.
How long did you have it for? Most hard-drive have 3 year warranty. So if it was
a technical failure, it will be replaced for free.