How to Fix Face ID Not Working on iPhone

Is your Face ID not working, showing an error message that it’s unavailable? This issue may occur more frequently than you’d expect, and there are numerous potential causes.If you’re one of the unlucky ones, don’t panic just yet. Try the following solutions before considering sending it to Apple Support.
Restart Your iPhone
Turn off your iPhone and wait for about a minute or so before turning it back on to see if Face ID is working.
To turn off your iPhone, go to Settings