my face id isn’t working how do i fix it

Read this:

https://support.apple.com/en-us/HT208114

Also try a force restart:

Force restart an iPhone with Face ID

To force restart iPhone X, iPhone XS, iPhone XR, iPhone 11, iPhone 12, or iPhone 13, do the following:

Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side button. When the Apple logo appears, release the button.

Hello there!

Please follow the steps in the following link for support with this issue: I

If an alert says Face ID has been disabled on your iPhone or iPad Pro