Chosen Solution

everyting seems to be working exept no picture on gamepad ,buttons are working.lcd has no visual damage.just replace the lcd or could it be something else ?

it’s possible a connector came loose. I would take it apart, and re-seat any connectors on the inside. If the problem still exists, then proceed with an LCD replacement. You can follow this guide to get to the connectors Wii U GamePad LCD Display Replacement

Agree with David if that doesn’t work then put a new LCD on it.