You can google this problem in. Try these things.
1) Can you use system restore?
2) Run a virus scan.
3) If you turn on your laptop and press f8, you get a screen that has different options, I think that one of the options is called advanced, you highlight the option with the up or down arrow keys on your keyboard since using a mouse is not an option. Once you get into advanced, of the options in the menu is to use start up repair. There is no guarantee that this will work, but it's worth a try.