Bike ownership transfer issue

I sold my second hand registered bike hero honda splendor, black colour, 3 yrs back to local computor shop person after my post graduation.. it was cash transaction & i gave bike & all relevant documents to buyer..I didnt took any delivery notes because of some bike transfer issue of my friend, i reminded about my bike..i rang my buyer to enquire about my worst fear..he did not transfer vehicle in his name instead he sold it to some1 through broker by giving my signed papers to him.. I questioned him how come he without transferring bike in his name sold to some unknown non traceable friends suggested me for safety to make back dated sale agreement on e stamp paper & convice buyer to sign it..which i did & buyer got convinced & .signed on it..i want to know is it just sufficient to have back dated e stamp paper or what more need to be done.. He dont know to whom he has sold his bike & whether he transfered in his name or not..I repeatedly called buyer to find out to whom u sold bike..but now he is not please need advice in this regard.