Getting my residence back from the possesion of my son/daughter in law

the owner of the building is my father , who has given me a registered power of attorney of a portionof the building. about 3yrs ago my son and my daughter in law , after the demise of my wife, entered the said flat and have taken possession of the flat, they have refused to allow me in the said flat, and I m staying in a rented flat. Till sometime back they were paying me some amt as compensation, but now they have stopped paying. I would like to get back my flat. I m 66 yrs old, had undergone bypass surgery, I m in great difficulty in meeting my day to day expeses and medical bills.