Hey. If you don't want to clean flash, try the following:
Boot up recovery and go to the file manager,
Then navigate to /data/system/
And look for the following files:
- gatekeeper. password.key
- gatekeeper. pattern.key
- locksettings.db
- locksettings.db-shm
- locksettings.db-wal
Delete them and reboot. You should be set. You'll just have define your password/pattern again.