If a mechanics lien was filed on a vehicle i bought and i bought the car and satified the lien plus price added from vehicle but a friend dropped off the car and their was no owner information how do you know who to send the ceritified letter to

I bought a car off a mechanic with a notarized bill of sale but when I registered it I found out the mechanic sent the certified letter to the person who dropped it off. Not the registered owner. Now I can't get the title or proper registration. I did get it registered but when it went to Frankfort I guess the registration got cancelled. I need to know what I can do to get proper registration and the title.