Getting an error when I turn on my computer

I have a Toshiba laptop. Yesterday when I turned it on, it went to the normal screen that says Toshiba and then it went to a black screen with a blue box in the center of the screen that says Enter Password with a black box to enter something. I have tried everything and nothing is working. If I enter something 3 times the computer will then just shut down. I have tired starting by tapping F8, by hitting F12, and by hitting F2 also by trying to start with the CD and holding C until the screen comes up. Nothing is working. Does anyone know what this is and how I can fix this problem?? Thank you!