Transfer of ownership

I had sold my 2 wheeler 1.5 yr ago by signing all the documents and surrendering my original RC . The person has sold the vehicle to someone without transferring the ownership. Also, I have misplaced the sale documents while constructing the house. After 2 yrs a girl had visited my house in my absence and told my husband that she had purchased the same vehicle from someone 2 months ago. She wanted to shift the vehicle to Tirupathi, but the cargo wanted the ID of vehicle owner. I was shocked to know that my ownership is not been transferred after signing all the required forms. Also the girl has told that she has lost the original documents and the person with whom she purchased the vehicle is not responding to her calls. I asked her to share his number so that I can call. But she didn't give. Later when my husband had asked her to apply for duplicate RC and come with the person from whom she has bought the vehicle so that we can once again sign the transfer form. Worst part is she had left without even sharing her contact details. Seriously I dono what to do and whom to approach for solutions to this issue.