Have you tried connecting an external monitor to the HDMI output port on the laptop, to prove that the GPU (Graphics Processor Unit) is OK?
If the external monitor shows a normal picture then the fault could either be a faulty video cable connection (at either end), faulty video cable itself or a faulty LCD screen.
If the external monitor shows the same display problem as the LCD screen of your laptop then there is a problem with the GPU which is embedded on the motherboard.
Below are two links which may be of some help, as they will show you how you can gain access to both ends of the video cable to ensure that it has not become partially disconnected due to the fall.
Here is a link that shows how to replace the screen in your laptop.
Here is a link that shows how to disassemble most of the body of the laptop.