im assuming absolutley NOTHING turns on (disks dont spin, lights dont blink, etc.). in that case, it might be good to buy a new power supply or test a different power supply on your comp.
to see if your power supply is faulty, take it out of your pc and put it into a different pc (one that you know works correctly). and visa versa. take the power supply out of the pc you know works correctly and place it in your pc and see if it works.