Oh, yes, it's a laptop.
Maybe I know, but I'm not sure I can explain. Try to push on the laptop around the keybord, see ? Maybe there is a bad conncetion between the screen and the rest of the laptop, so try to press around the keybord to reconnect it.
Do you have another comptuer home ? Or maybe just another screen.
EDIT : Maybe it's the BIOS, but if it is you should see the black screen be lighten up, and turn grey.