HOW CAN I RETRIEVE DATA FROM A BROKEN USB HARD DRIVE?

My Samsung 12GB Pleomax USB hard-drive just... stopped working... ironically on the day that i was about to transfer all my data to a back up drive just incase something should happen... haha.. (i'm actually about to cry). No computer will recognize that it is plugged in. At first it says that there is and UNKNOWN device that isnt gonna run. Then i cant find it anywhere on the computer or find a way to get it to open up with any type of software. I have 8,000 some odd photos and graphics i created on there aside from all my other cr*p and i'm desperate. SOMEONE PLEASE HELP ME! HOW DO I RETRIVE MY DATA FROM THE SAMSUNG PLEOMAX 12GB USB HARD DRIVE??!