1. If the cheque date has not complete three months time , present it again and send a legal notice demanding the money , and proceed in the court with a cheque case under 138 of The Negotiable Instrument Act. for Rs. 50,000/
2. You can file a civil suit of recovery after sending him a legal notice .
3. to establish the transaction of a HAND LOAN the bank details are enough , you need to prove that there was a verbal agreement and contact to return the money.
4. Your parents can be witness
5. The returned cheque and the communication details in chats also can be produced as evidence.