With any luck, it is just a loose connection inside. However, it would still need to be opened up to resolve that. Should it turn out not to be a loose connection, then you are going to have to replace the display.
If it is under warranty, dropped or not, try contacting the manufacturer about a repair/replacement. If no longer under warranty then, again, either you can do the replacement of the display, or you can take it someone to do it for you.