Sister in law took my Father property papers and Gold ornamaents at her home without informing them

Dear Sir , My Father is bedridden and Mother has got paralytic attack recently . My sister in law without informing to my parents took their property papers and Gold ornamaents at her home. The property is belongs to my father's name only .My father has got two children .My brother is elder one and I am younger one .My Brother passed away before 2 years due to Brain strock . Till date I took care of my Father , Mother even brother also I always take care during these three ones whenever hospitalised and no one attend them as they dont want to spend money. Since Two month I request my sister in law for returning my parent belongings but she send Notice to me for not interferning in this matter. also ask me to apologies for giving NC in police station . My all cousine relatives also intrested in my Father's property . I wish till my Parents are live need to use their money for their rest living . My Father and Mother also wish that I will take care of them in their rest of life. . I wish they will not dependent on any body as they have their own money with them . Because of this incident my mother is depressed and she is not feeling well in these days. After repetative instruction to my sister in law is not giving their belongingds. Pl guide me further for proper action Thanks Rutuja