More than likely a cable came loose to the display. To test get a HDMI to Mini HDMI and connect to a TV, if it works the 2 things that coul be wrong are 1. loose cable, 2. Damaged display.
If you want to open it do a search for how to open an ASUS EE Pad, or ASUS transformer.
Ifyou don't want to fool with it and you are in the US there is a company in San Diego that repairs TF's.