Booting Problem

Hi There,

I've Emachines with Intel Celeron 2.2 GHz. It was working fine..i've got my database on that machine..so i keep it on always..it was working fine before yesterday..when i came yesterday it was not on...and when i tried to switch it on..it shows power on...but power light on the front of CPU flickers constantly as well as num lock light,caps lock ligh and scroll lock ligh also flickers constanly...nothing get displayed on the screen..even monitor's power switch is showing on..but it doesn't boot..i can't see anything..no beep sound and nothing...please help me what can be the problem?

Thanks...