Can’t reset Face ID. After press set up Face ID camera doesn’t work
Can’t setup Face ID
The link on top of this page which you had visited, before posting this question here, is shown under the "Related Article” that may have given you an answer.
You need to mention which part of the article was not clear to you.
If you still need help, reset Face ID, then set it up again. Go to Settings, tap Face ID & Passcode, then tap Reset Face ID. Next tap Set up Face ID to set it up again.
If Face ID isn't working on your iPhone or iPad Pro
If your iPhone has a history of Camera replacement / Repair / Service from an un-authorised service provider then the only option that you have is to take the device to...
Take your device to an Apple Retail Store or Apple Authorized Service Provider, or contact Apple Support:
Find Locations - Location Selector - Apple
Contact Apple for support and service - Apple Support
Get a Genius Bar Reservation and Apple Support Options - Apple
Contact Genius Bar.
Manage Reservations - My Reservations - Apple