HELP my computer is messed up!!! PLEASE HELP?!?

ok so i wake up today and my computer is off. (windows xp 2000) then when i turn it on i hear the fan going and stuff but the screen reads no signal, also my keyboard is not working like there is no lights when i press caps lock or num lock..... and the mouse doesnt work either..... so when i turn on the computer the pc looks fine and it sounds fine but the moniter and key board and mouse dont work.....