Try a force restart. Quickly press and release volume up, quickly press and release volume down, press and hold only the side/sleep button for 15-20 seconds (do not slide to power off) until the display goes black and a white Apple logo appears and then let go of the side/sleep button and let the phone boot up.
Try a force restart. Quickly press and release volume up, quickly press and release volume down, press and hold only the side/sleep button for 15-20 seconds (do not slide to power off) until the display goes black and a white Apple logo appears and then let go of the side/sleep button and let the phone boot up.