so, first you have to go to the google play store (on a computer) and install the android device manager, that is by google, remotely.
then go to the android device manager login (you can google it because I don't have enough posts yet to post links) and press the "lock" option.
that gives allows you a the ability to set a one time unlock code.
once you set the unlock code through the device manager, unlock your phone with that passcode that you just set.
then immediately go to your settings and look for the "fingerprint" option.
open that and look for "change alternative password" open that and enter a new alternative password (something easy for you to remember)
THEN (yes there's more) you need to re-enable the fingerprint mode (if you had it previosly set) by selecting "screen lock" under the same "fingerprint" menu.
re-enable fingerprint mode by swiping your registered fingerprint.