Unlocking the system as administrator

Unlocking the system as administrator

Hello. I have problem with unlocking system and I can't find answer in manual.
I've found my problem at chater "User Administration" - "Operating during Runtime":
-After entering a not existing user name the system is locked. This means, that no user can operate the system any longer. Only the administrator can unlock the system.
I can't find where can I do it. I think I've watched everything in project properties and user administration.
Thanks.

This is a migrated post! Originally posted on 12.06.2014 by user ktech. Please be aware that information can be outdated.