What exactly are you trying to do? If your phone won't read your finger print, you should only need to enter in your back up password you made when you set your finger print. It's not the same as your Google account password unless you set it the same as that one.
If your phone is locked and asking for a user name and password, it will be your Samsung Account info.
Please note, don't take this personal, but if this device has been stolen or found, you should just turn it into the carrier and give up.
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