Extensive instruction (only in german)
Accountsperre - Ursachen und Lösungen
Essentials in short
Your account may have been locked for different reasons. This document explains the causes and steps that need to be taken in order to unlock your account.
If your account is locked due to a change of password, this is probably because your old password is still active on one of your devices. In that case, check all of your devices connected to a network (e.g. notebook, Smartphone, tablet) for active passwords.