If you lock a topic of your own creation and want to unlock it later, this will definitely work.  But if a topic is locked by an admin or moderator or you want to unlock a topic created by someone else then you can't do it anyway because you are a normal user so you don't have any special powers like an admin or moderator. So if you want to do it then it will definitely be a futile attempt.
One thing I don't understand is why you are trying to unlock admin locked topics. did you create that topic?  Or do you have some other purpose? and which topic are you trying to unlock?