IT all depends on the state you live in. In most states a landlord cannot retain property owned by a tenant. If you can prove the property is yours you should be able to get it back although you could be charged a storage fee in most cases.
If you have reciepts or any kind of proof that the items are yours, than you can call the police to go over there and collect your belongings. If you do not, and they have been in his possesion for more than 30-90 days he can claim them.