When you say "Its not working" what do you mean exactly?

Is the power light on?
What colour is it (Normally blue, green, orange, etc. Red means "protection" is on normally)
Have you checked the fuses in the amp?
Are ALL cables connected properly and connected to the right place?
Did the live wire touch the chassis of the amp with the earth connected?

When ever I had problems with my stereo system I found removing it and reinstalling it completly stopped any problems.