my I5 phone's screen is locked. The alarm was set last night and now I can't turn it off

My I5 phone's screen won't respond to 'touch'. I set the alarm last night and now I can't turn it off, I can only 'snooze' using the volume controls.

Model is A1533

I have called the phone and the touch screen does respond to allow me to answer the call but when I end the call it returns to home screen and is still frozen.