My HP Dv4 Pavilion laptop is no longer under warranty but has been working fine until I powered it up last week and cant get anything to come up on the screen. the caps lock and the scroll button are blinking and the other lights on the keyboard are lit up but nothing will display on the screen. also, the wifi light at the top of the keyboard and the sound light will not change when I tap them. They seem to be frozen. What can I do to fix this problem?