Can't use Face ID in my iPhone

If Face ID isn't working for you, there is most likely something wrong with your TrueDepth camera. First, look at these two articles for help. If that doesn't fix the issue, then make an appointment at the Genius Bar to have your camera issue diagnosed.

If an alert says Face ID has an issue on your iPhone or iPad Pro - Apple Support

If Face ID isn't working on your iPhone or iPad Pro - Apple Support (AZ)

Make an appointment at the Genius Bar to have it diagnosed.

Genius Bar Reservation and Apple Support Options - Apple

Hello,

Apple has several documents helping you with Face ID.

This Support article is specific to seeing an ‘issue’ or 'disabled' Face ID alert, and explains what to do when you see that notice or an issue with the TrueDepth camera. --> If an alert says Face ID has an issue on your iPhone or iPad Pro - Apple Support

Unless a software update solves the problem you may need to have Apple take a look at your device. Use this link to set up an appointment —> Genius Bar Reservation and Apple Support Options - Apple and this one to get a repair estimate —> iPhone Repair and Service - Apple Support

If you don't see a 'disabled' message but do have general issues with Face ID not working properly, explore the list in this article of things to try: If Face ID isn't working on your iPhone or iPad Pro - Apple Support

If the first 8 don't solve the issue then use #9, contact Apple.