Gatewaygt5220 computer doesnt turn on

Hello,
my computer gateway gt5220 computer is only 2 1/2 years old. Suddenly it just doesnt turn on anymore. The light doesnt come on, the screen is not reacting and there is no beep signal.
I looked inside the computer and could see that the vans are running when i turn on my computer but anything else seems to stay dead.
What could be the cause of the problem and how can I fix it.

Thanks for the answers.