My HP laptop started having this issue and it was after a conversation with a friend that it has turned out to be a common problem with the NVIDIA chip with this line of laptops. He commented that it does not affect the output to other screens, only to the laptops own display. Apparently (though I have not seen this) the chip burns or overheats the local area on the motherboard and can no longer run its own display.
I had fortunately just bought a docking station for this model of laptop and I have been able to hook it up to an external screen, keyboard etc up and my "laptop" is now a fully functional desktop.