How can I restore the light/glow on my tablet?

The other day my zenpad fall on the floor, it wasnt a larger fall, it didnt cracked, but the screen stoped glowing, it doesnt have any light. You have to turn out the lights and you can see how the tablet works perfectly, it plays media, apps but it has no glow. I wanna know if there is something i can Do, or if i have to change the display. Thanks!