Hi. My name is***** you see the icon on the screen that looks like a keypad like in the attachment below?
Click it and then enter your PIN.
Let me know the result please.
Is the power icon displayed in the lower right corner of the screen?
Or are you able to click Sign in Options ?
Or hold down the power button on the laptop for 4 - 5 seconds to turn the laptop off
then start it up again.
Does your screen have Sign In Options (attachment below)
I do online support. I know you don't want to lose your work but if you don't have a way to enter your PIN
and Windows Hello has you blocked I don't see any other way but restarting to get the screen to a state
where you can enter your PIN.