I would first recommend holing the power button in for about 5-10 seconds. That should just cut the power to the laptop. After that try restarting it and see what windows tells you about its last boot. If it really was as bad as you say it was I would probably chose the option that is "last known good" That will be your easiest chance at getting your computer working again. If it doesn't help post back with some more information like what kind of computer you have, or where you bought it if you do not know what parts it has in it.