Vehicle Sold But Not Transferred

I have sold my Activa in 2014 whose engine asking for repair so I sold it to my known mechanic in good faith of Rs. 10000 as he told me that he would repair it's engine and sell it and also transferred to the name of that person. I have no proof regarding the sale, and last month I check it online that it's still standing in my name and I called him and he clearly denied that he didn't buy Activa from you and saying that you are telling lie. I requested him please don't do that, remember to whom you sold it, but he is corporate me, so I filed an application to the RTO as well as the SP office via registered A.D. Now I got a call from my area chowki and the police ask me what you want now, where are you from the last 7 years. I said to him that I admit that it was my fault but now what to do. But he didn't list, I am saying to him that I want that from now on the whole responsibility of that vehicle the person who has it, but he is not ready to listen to me, he calls me and ask me to come to chowki.