System dont start at all Dimn 9100

Hello every one..

 I have Dimenson 9100 more than two years and it was working ok til last nite.

I turn off system as usual and it was fine.

But today  when turn on my system.....it didnt start. cpu fan is running, NIC light is ok and some kind green light on motherbord.  beside that every thing is off. mouse, keyborad also not working. Monitor totally black. i tried every thing as much as i know.

Plz help me if any one konw that what went wrong???

thanks for help

kev