If you turn your craptop on and you get only a black sceen then you probably got a acer/hp/dell/gateway/sony craptop and it's most likely dead
1) is the fan spinning?
2) do you have any beeps, blinking leds?
3) how old and what is the model of the lappy?
It's probably not under warranty anymore so you'll most likely have to spend 200-300 $ on a new motherboard (80% of the time the motherboard fried because of overheating)
So go to a local store and buy an Asus: much better laptop than any other brand
Good luck