The controller board is completely fried? Won't boot/post/etc?
If that's the case, you have two options:
(a) Buy the exact drive over again, and switch the boards (costly)
(b) Send it to a commercial data recovery center (very costly and will void your warranty as they hack the drive apart)
However, if the drive is still bootable, then there are lots of ways of doing it yourself. I've used software such as Easy Recovery (on formatted/deleted files) and Spinrite (on crashed HDs) and they've worked great.