I have a HP Pavilion dv7. It has taken a few tumbles lately with my 3 year olds help. It also overheats frequesntly even after cleaning out the dust/dirt and everything else.
Last night I fell asleep with the laptop on me and woke up to a loud crash (which apparently was the laptop going overboard when I rolled over). Today the screen has some funky coloring going on.... there are some green lines where the black is, some yellow lines through reds, and cyan lines through the dark blue. The tricky part of it is that it's not in all of the same color. Playing candy crush on facebook the red candies are now mostly yellow... but if I have another screen up that has red in the same area is red. I can't find any rhyme or reason to why some of the area's are lined with different colors and the rest of the screen is clear as day.
sounds like you need to take it to a shop for repair... i doubt this is something to do with software as it got dropped.
you may be looking at a new screen or it may just be a simple fix like replacing a signal path that connects the screen to the rest of the internals.
but it will take a pro to figure it out and repair it so i doubt it will be a cheap fix.