Admin PW & Touch ID

Since installing Big Sur on my MacBook Air (13" 2018) i can use my login admin user name and PW & can sign into my computer. The same admin logo in PW will not allow me to unlock the security system lock in the bottom left corner in system Preferences. I only have one admin name & no guest. How can I find out if there is another in my system that will work or fins the related password. I have already reinstalled BigSur with no change. Also Touch ID is not working