|Yes, you dropped it and did physical damage to it. It could be a dozen different broken points. Your best bet would be to take it to a shop and have them check it over.|
If you really want ot try and troubleshoot it yourself and are up to dissecting it, take it apart and look for loose connections between the video circuitry and the LCD screen such as ribbon cables coming loose. Start at the motherboard then look at the connections that go to the actual screen. If you are not real machanicly inclined, or have never worked on laptops before, I would not suggest doing this on your own. You could end up doing more damage then good.