Laptop showing blank screen?

I need help! whenever i turn my laptop on the screen is completely black, it goes through the loading up screen i can see that fine but when the screen should be showing my desktop it isn't i can press ctrl, alt ,del and that screen shows but that is all, but the desktop works in the background as i somehow managed to open msn news and listened to a video but still couldn't see anything. the same also happens when i try to boot in system restore mode. any ideas on how to fix it?