My Wii U Gamepad doesn't respond using touch screen and buttons

So recently a family member broke the Wii U Gamepad. I don't know how, but the screen, which switches on doesn't respond to touch.

The buttons except start, select, power and tv don't work.

How do I fix my gameplay so all the buttons and screen works?

EDIT: I forgot to add that we have disconnected and reconnected the battery, but it still didn't work.