Assuming the landlord was storing your personal property (as opposed to providing a place where you could store your own property) he became a "bailee" and responsible to safeguard your belongings. Whether this is in fact true is a matter to be decided by a judge.
You may sue in Small Claims court for up to $10,000. However, it will be up to you to prove that the lost property was in the landlords custody as well as the value of the lost belongings. Contact a attorney to assist you in preparing a claim.
Mr. Freitas is an attorney licensed in the State of California. The answer provided here is general information and not intended to be specific legal advice. There is not attorney client relationship created by Mr. Freitas' answering any question on this website.