help. screenlocked.

I changed my screen lock to fingerprint, got interrupted.   When I finally got the chance to complete the fingerprint,  I went to open my phone it is asking for a passcode, at least 4 characters, 1 letter.  I haven't a clue what that is and have made so many attempts it is 24 hours in between attempts now.  I tried a YT video with codes and it didn't work.   HELP.  7 days locked out