Hello,
1) You have taken the right step in sending the legal notice to your brother demanding the money.
2) You need to follow up if he does not comply by filing a suit for recover of the money lent to him. Attach all the proofs of the bank transaction as proof.
3) As he has landed property you can press for attachment of the property against the debt he owes you.
4) Do not be concerned ; you will get your money back. Wait for his response to thee legal notice. Once you file for the recovery it is more than likely he will come up for a settlement.