These are instructions for fixing a Seagate 7200.11 hard drive that is stuck in the BSY state. This can be determined by the fact that it won't be recognized by the computer's BIOS. If your drive is detected, but shows up as a size of 0, then you're drive has a different problem and these instructions will not apply.
If your Seagate hard drive was bought at retail, then you are lucky. Seagate will fix your drive for free! See this Seagate Forum Post for more information about how to contact Seagate Tech Support to have them fix the issue for you.
If your drive is an OEM drive, then you're probably out of luck. My drive came with a Dell computer. It was under warranty, so Dell sent me a replacement hard drive, but they wouldn't do anything to help with data recovery. I was stuck with either paying someone to have it done, or doing it myself. I'm a pretty frugal guy, and the DIY method didn't sound too intimidating, so I gave it a try and was successful in un-bricking my drive.
These instructions are meant to be fairly comprehensive, with lots of pictures. After reading through them once, you'll probably want to refer to the Short & Simple Instructions for fixing your own drive.