Your hard drive may not be dead... yet. BUT... If not dead, it's on the verge of dying.
It can't be repaired as it's probably an internal, controller, problem or a surface problem.
You can't swap another controller as it have been customised to that particiliar drive and another is not configured in exactly the same way.
If it's a surface problem, some data IS destroyed, hopefully, it's system and OS files that are gone, maybe not your datas.
Your only option is to do whatever you can to salvage your datas.
As your drive is about to die, try to go for the files you can't replace first. You are not sure if you have enough time to recover all your files.
You need to remove the drive from that computer and connect it as a secondary drive in another computer.
Have it recognised in that computer and, if it works, transfert all your data to another drive.
Copy all folders except the Windows and Programm files folders.
The best destination is a new, freshly formated, drive.
If that other computer can't recognise the drive, you can try with another computer. But if 2 computers fails to access the drive, it's very probably dead. Sory for your datas.
Alternative option:
If you can't move the drive to another computer.
Find any "Live CD" and use it to boot.
From that alternative OS, try to copy as much as your files to an external drive or another computer.
Electro
January 2012