That's about as useful as going 'My pc stopped working, what's wrong with it?'
We need details... did you install any new software or hardware between shutting it down and it refusing to start up, do you get any beeps from your motherboard at startup, what other parts are in your pc...
thanks for reply no software or hardware was installed before shutdown also there was one long beep then three short beeps after restart. i removed all the ram then resat them done this with graphics card also. still getting beeps.