Chances are the screen in fine. The action of dropping must popped one of the ribbon cables loose. Even though the 2ds screen(s) is actually one big screen, they have two separate cables, one for the bottom and one for the top. The back light and touch screen are operated by different ribbon screens and not related to your issue.
Use a precision screw driver and remove the bag battery cover (2 screws). Remove the battery. Remove the back cover (8 screws). The connection to the ribbon cables are just located underneath. These are the two wide cables located in the middle of the board. You can test fairly easily if this is the problem.