I think I might have just killed my external hard drive [View all]

I was not careful, and plugged the power adaptor from my 12 V PC into my 9 V External Hard drive. The light is still on when I put the correct power supply on it, but it is no longer being recognized by my PC. I have tried a second PC and still no luck. I know the power supply is good because I tested it on another external hard drive. I tried two separate USB cables. I don't have a another external drive that uses this type of USB, but my cables do allow recognition of a MP3 player.

Any suggestions?

It is a Western Digital 1TB hard drive.