Owner is denying to refund deposit amount

Hi Gentlemen, I was looking for a flat and was contacted by owner of a flat saying that it is sharing 2 bhk apartment. I work in night shift and 1st May was the date to shift in so I shifted my luggage 29-30 April. Before shifting I paid 12,500 as advance rent. It is a 2 bhk apartment, I was allotted single occupancy room and 2 guys in master bed room. Owner promised that the documents would be taken care off once I shift-in. On 4-5-6 May, I was visited by my family and Owner did not allowed them to stay with me saying this is a paying guest apartment and you are not allowed to have visitors for these many days. So, on 5th May, I informed the owner that I would be vacating the flat by 12th May and Owner promised to return my deposit by 10th June. On the moving out day, my room mated were sleeping as I shifted early morning and owner did not picked up my call. I left house informing owner via wahtsapp which he did saw the same day but did not replied back. Now, It's been 8 days I am calling him and they are not taking/replying to my messages. Today morning I texted them that I am going to complain against you in police, in return he is saying that he will log a complaint that I was staying illegal in their property and I have stolen few valuables from their house. Also, claiming that I did not returned the key and did not informed while vacating the flat so he will not return any money. I've got all documentary evidences with me, including whatsapp chat in which Owner has said he will return my money, bank transfer details, and any other related proof regarding this. What shall I do to get my money back ?