As soon as I press the power button on my computer it says that I have to type a password to access the computer. I can't even come to the login screen, it's totally locked. I guess one of my roommates did it. Is there any tool at all that can help me? it's an HP laptop..

Oh... Its a laptop? Thats hard. If it was a desktop i would say open it up and clear the CMOS, but with laptops that is a rather dangerous and hard thing to do. The first thing to suggest is ask your roomates what the password is and have them remove it from YOUR computer. Otherwise you might have to take it to a computer repair shop to see if they can reset it.