If your iPhone or iPad isn’t responding and you can’t turn it off and on, try forcing it to restart. Note that this will not delete any data.
For iPads & iPhone 8, X, and newer:
Quickly press and release the volume up button.
Quickly press and release the volume down button.
Press and hold the side button until the Apple logo appears, and then release. (The screen will temporarily go black as the iPhone/iPad shuts down and reboots.)
Keep holding the side button until you see the Apple logo.
iPhone 7/7 Plus:
Press and hold the sleep/wake and Volume Down buttons simultaneously for at least 10 seconds.
Keep holding both buttons for about 10 seconds, until the Apple logo appears.
iPhone 6/6 Plus/6s/6s Plus/5/5s/SE (1st Gen.):
Press and hold the home button.
Without releasing the home button, press and hold the sleep/wake.
Press both buttons simultaneously for about 10 seconds, until the Apple logo appears.