I am typing on my iPad because my iPhone 12 is not responding to apps or turning off I can’t do anything

Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

Axel F.

Try a forced restart: press and release the volume up button, immediately press and release the volume down button, hold in the side button until you see the Apple logo then let go of the button.