I rented an apartment a year ago, and I received a phone call from the owner of the apts. that I owe money?

The owner said that he fired the property manager because he didn't keep very records and that he & his wife are now managing the property and according a partial ledger that they received I owe them money. I never received any kind of statement from the former property manager stating that I owed money. I left on good terms. Now for some reason I am getting a call from the owner threatening to turn me over to the collection agency. Although, he can't show me any doentation other than what he worked up that I owe money. I don't have records of what I paid that was a year ago. How can I get resolved this?