Clean the screen with a soft cloth
Turn on the device
Open a touch test app or screen test website
Tap different areas of the screen
Swipe in all directions
Pinch in and out with two fingers
Press and hold on multiple spots
Check if all touches register correctly
Check for dead spots or unresponsive areas
Check for ghost touches or random input
Test the edges and corners of the screen
Test multi-touch gestures
Restart the device if touch is not working properly
Update the device software
Try safe mode if available
Compare touch response with another device if needed