Owner not returning deposit even after vacating the house

I called and even send an sms regarding a 1 month notice to the owner and also paid the rent for that month. Thereafter I and the broker who signed the agreement between us called him several times for two weeks but no show. After two weeks he picked the brokers call who asked him to show the house to the new tenant and return me the deposit. Immediately he called me and said he wants to change the broker and will only return me the deposit after he gets the new tenant. I had to vacate the house in the mid month due to personal reasons and had to pay the same deposit amount at the new place. I continuously pleaded him to return me the deposit from one hand and take the house keys from other hand. But he continuously denied me and the responsible brokers. He says he has used the money and has no money to return and will only return when he gets a new tenant. I am afraid if he doesnt get the new tenant he will not return my deposit at all. I also gave him an option to return the deposit via post dated cheque which he can deliver via someone he authorises or he himself can come down to Mumbai from Bangalore and take the keys from one hand and return the deposit from another hand. He is not ready for mutual agreement and cooperation and instead sends me threatening sms which correctly indicates his no intention of returning me the deposit at all. he also mentions he will deduct the rent until i give him the keys back. He doesn't assure me anyways to give me the deposit even if i returned him the keys. What should be done in this case?