The lanldord has a perfect right to enter his property. He gave you notice (written notice would have been better). Why does he not have the keys to enter? Why will he have to break or change the locks to get in? You apparently changed the locks and failed to give him a key. This is a violation by you, not him, and he has every right to enter, and to bill you for the locksmith. Sounds like you owe him rent as well. Good luck.