Hello,
Thank you for posting your query.
In order to enforce the agreement entered between the parties, you may do the following:-
1. File a civil suit for specific performance of the contract before a civil court of competent jurisdiction. In the court decrees in your favour, then the seller will have to get the sale deed registered.
2. Additionally you may file a criminal complaint for cheating so as to create some amount of pressure on the other side.
Regards,