My Face ID not available check it now

There may be something wrong with your TrueDepth camera. Please view the following articles. 

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

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

If the above doesn’t help, please make an appointment at your nearest Apple Store Genius Bar or Apple Authorized Service Provider for diagnostics. 

Genius Bar Reservation and Apple Support Options - Apple 

See this for some suggestions:

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

Regards.