I don't understand, numnum, but I remember your previous threads. If it's your house and you have bought it, how come you now say "it's his brother's house"? Have you bought it, or not? Why has the original owner still got keys?
There was a thread on here a few days ago about leaving things when you sell once the new owner takes over, those things belong to you, so the brother has stolen it if he took it without your permission. That's stealing, but how did he get in?
a) who actually owns this house?
b) why don't you change the locks?