My Face ID is not working

Disabled Face ID alert on your device

The link on top of this page, under the "Related Article” is the process to be followed if nothing works then please read --> "What to do Next" section. if nothing works as per the instruction given in this link --> If an alert says Face ID has been disabled on your iPhone or iPad Pro

Just reset one for your dedvice. If it still doesn't work, just take your device to the nearby Apple Store and ask for the help.