I'm sorry to have to advise you that in the situation you describe there are three components - the hardware (hp pavilion), the operating system (Windows) and the user. Of the three possible causes of your problem my money is on the third. lol. seriously though - a friend of mine had her cat walk over the keyboard and it caused a similar problem. You "simply" have to try and find by trial and error what key combination has caused your problem. Do you have an external monitor which you can plug into the external monitor socket to see if the display appears on there?