Landlord not returning my deposit money

Hi On 1st of Jan 2016 Me and my two frnds taken the 3bk in a gated society. our agremnt was for two years and our owner taken the two month security as well. But due to some issues in flat i have informed him that frnds of my flat mates taking drugs and bunch of guys coming anytime in flat and dsitub every day but beside realoving the issue suddenly on 25 of frb 2017 at 11 o clock he told me to vacate the flat by next day. he Threat me and told me that if i will not vacant the flat in next day he will call the police. That time he told me that he said other two girls also for vacating the flat and he was the retired kernel so he was using his all power for my vacating. Because as being a girl i was very scared that time and because of the owner behaviour i vacated the flat with all clearence of electrity and maintaince bll . i have everyting in written in the communication which was haapen with my lanlord. That time he return hlaf of my despoit and left he said that i have some warranty card of his aqua purifier and when i will deposit him he will return my half deposit. But now when i am returning his warranty card he didnt reply me and not returning back my deposit. what should i do now.