Face id

Who replaced the screen? If it was Apple, take it back and let them know it's not working.

If you replaced it or a non-Apple authorized repair shop replaced it, it wasn't a genuine Apple screen and it may not work.

Have a look at these two articles -

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

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

If Face ID isn't working on your iPhone.

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

Take it back to the shop and let them know, but chances are with a non genuine part they may not get it to work.