Hi i have a n620c evo compaq laptop. Just recently i was downloading a program for a few days and keep it on. Then it suddenly froze, so i use the switch off power button on the right top corner to shut it off. Then when i go to reboot, the power LED is on there is power, but nothing else function. I get a black screen and it seems like it's not even reading my HD. If anyone can help and I thank you in advance..