Help! External HD not mounting.

Been using an Iomega 750g minimax HD for back up of photo's, music etc for an old Macbook laptop running OSX 10.4.11 but all of a sudden, it's decided not to mount on the desktop. I think it's just short of 2 years old and wouldn't expect a drive failure at that age. It's making some sort of disk noise, a bit like a stuck record, if that's any help.

The last time it did it, i ran some software called diskwarrior, which seemed to do the trick (it did a rebuild or something like that) but it's not detecting the drive now, so i'm stuck for ideas as what to do next?

Anyone?

That stuck record noise is pretty bad. Generally it means the drive is completely dead, especially if you can't even see it anymore.