Yes, you can file a criminal case against the person who has not repaid your loan under Section 420 of the Indian Penal Code i.e. the offence of cheating. The first step in filing of the criminal case is lodging of FIR in the police station of your jurisdiction. Once the investigation is concluded a case can be instituted in a Court of appropriate jurisdiction preceded by a legal notice to the accused. A criminal case acts as an efficient remedy owing to the retributive nature of the punishments and penalty.