Recovery of rent money

Tenant left the house without informing me and took the keys of house with him. Only after the interference by police, tenant handed over the keys to me. But after repeated promise that he will give the five months due which he had not paid till now .Rent agreement is till April 19 and he vacated in Dec 19.l had given him the legal notice as per the address proof given by him during agreement but now twice the legal notice is returned mentioning that no one is there in the house. Please advise now how to go ahead and recover the money from tenant. Please help