Since you haven't provided any evidence supporting that you were the previous owner, or that you were supposed to get the property back if/when the gang closed, i'll assume there isn't any.
So since you don't have any evidence of that, then we can't do anything. We can't give you a property because you say it's yours. That's rather logical isn't it?
This is your own fault since you didn't create a contract with the gang leader.
Kain has created a forum section where such contracts can be created, so hopefully people wont find themselves in a similar situation again.