Sister Taken All The Possession Of Father After He Died

Hi My Father expierd in the month of February 2024, and my sister has taken his mobile, car and every document (Property Related) in her possession. She is not returning my and my Mothers' Gold. My mother is also no more. We are four sister and second sister done this. Sister stays in Etawah (UP). When my father was having corona at that time she has pressurised my father to make her join account holder. My Father died suddenly and the amount/FD is in bank where she's also the Joint account holder. I want all 4 of us should get the share. What should I do please advice. REgards Gargee