if you purchased the land then your son had no right to sell that off and therefore you can challenge that sale deed and file a criminal case against your son for cheating. I wish to take up your case if virtual courts are available in your local courts 9013429126
You can seek money from your son for your maintenance from court.
For further queries, you can contact me on email@example.com
You can file suit for cancellation of sale deed
If you want legal advise then you can call me on mobile no 9359867870
Advocate IRFAN SHAIKH