Legal remedy to recover security deposit from landlord

I rented a flat in sector 23 from 01st June 2017. The owners were very elderly and quite rude from the beginning, but I thought that it was typical according to their age and trusted them. I was to be married in the same month, due to which I had to leave for 15 days for my hometown. Prior to leaving, I had signed the rent agreement about which they became very rude and adamant that I only sign and not read it fully. They kept the rent agreement with them saying that the property is in the name of their son, and they will give me the agreement after he signs it. I shifted with my sister, so I did not have much choice than to sign and give it to them based on trust. After I came back on 01st July 2017, after being married, I asked them to refund my security deposit of 17,000/- as I want to move out. They absolutely refused and asked me to either pay the rent for the July month or vacate the flat immediately. So we had to move out on the same day. Please help get my deposit back! :'(