Hello, thank you for reaching out to Microsoft Q&A.
Are you being asked to enter the A1B2C3 Challenge Phrase on the Windows Hello Sign-in screen?
So, after entering the Phrase, do you get the option to reset your PIN?
If this option is unavailable, try switching the sign-in method from PIN to Password. (If you have used it before)
If signing in with a password is not an option, you will have to boot your PC in safe mode. To boot your PC in Safe mode,
1.Start your device and wait for the Windows logo (or the manufacturer's logo) to appear.
2.As soon as the Windows logo appears, press and hold the power button until the device shuts down.
3.Turn your device on again and repeat step 2.
4.Turn your device on a third time. Windows should display the Automatic Repair screen.
Select Troubleshoot > Advanced options > Startup Settings > Restart.
Press F4 to boot your PC in safe mode.
If you are able to log in to Safe mode successfully, you can try resetting your PIN or create a new local user account from there.
Let me know how it goes.