Hi
You should follow the following procedure:
1) According to the Indian Motor Vehicle (IMV) Act 50, the transferor (seller/You) are required by law to inform the Regional Transport Offices (RTO) within 14 days of the transfer of ownership.
2) Similarly the Act also instructs the transferee (buyer) to inform the RTO about the change in vehicle ownership and produce all the required documents within 30 days of the transfer.
3) So what you need to do now is that
a) Submit an application for change of ownership along with the following in the Regional Transport authority office where you previously registered your vehicle along with
b) Copy of Registration certificate
c) Copy of Form 29 (Notice of transfer of ownership of a motor vehicle) signed by you and buyer.
d) Copy of Form 30 (report of transfer of ownership of a motor vehicle) duly signed by you and buyer.
4) If you do not have copies of Form 29 and Form 30 duly signed by the Buyer and seller then the option you have is to advertise in 1 telugu and 1 english news paper and submit the same instead of Form of 29 and form 30.
5) Now you can also log on to the portal https://tgtransport.net/TGCFSTONLINE/Reports/VehicleTransferIntimation.aspx and fill in the transfer details
and visit the RTO office within 7 days from registration and submit the documents mentioned in point 3 or 4 as is applicable.
6) In case there are no pending traffic challans against the said vehicle registration number then there is no need to file a police complaint as Only the Regional transport authority has the powers to either prosecute the buyer or levy fine on the buyer for his failure to comply with the rules.
Hope this information is useful.