Property Related Fraud !

The story starts like back in 2022 my grandfather passed away and in his will all the FD were given to my grandmother (although relation between my grandfather and grandmother was not good enough), only my dad has right on the house. Now few days earlier my grandmother also passed away ... (I along with my family lives in another state , and my grandmother lives in another state ) so requested grandmother as she was ill too, to come & stay with us, but she always refused and said will come later on but never came so she was taken care by her brother and her family side for almost three years but now after her death all the gold, FD's , her original documents are missing even her brother and family left the house on the same evening after the cremation was done asked them many times to tell them about details about where are the documents and all stuff but still they say that they don't know nothing about this what should I do now??