Wondering why the touch screen display did not respond suddenly untill restart? Tx..

Being an electronic/computer type device that can happen and often a Simple Restart or Reset (as described below) will often cure many such ills.... If the problem persists... Connect to iTunes on your Computer and Restore

Reset ( No Data will be Lost )

Press and Hold the Sleep/Wake Button and the Home Button at the Same Time...

Wait for the Apple logo to Appear...

Usually takes about 15 - 20 Seconds... ( But can take Longer...)

Release the Buttons...