Face ID stopped working

Hi I have Face ID set up on my iPhone 11for over a year no problems . It suddenly stopped working two days ago . When I check in settings set up Face ID is highlighted in blue so it looks like it was removed. It wasn’t. When I try and set up I got alternate messages of lower iPhone or Face ID not available try later. I have done force restart and the problem persists as in it keeps saying lower iPhone . I could be photographing my feet at this stage as it continues to tell me to lower iPhone when my face is clearly outside frame . I finally get the message that my face is no longer within frame. The notch is clean and not obscured and front camera working 100% . Obviously my face is not covered in anyway . Passcode still working but I miss the Face ID any ideas