Mutation

Dear Sir/Mam, My parents (Mom and Dad), when I was in the age of 5, passed away in an accident, and I am the only son. There are no other relatives. We were just a family of three. The death was sudden hence there was no will. There is a property in my father's name which I now want to transfer to myself. I do not have legal papers other than the property tax receipts (on my father's name) from Nagar Nigam. Now on behalf of my father, I am paying the property tax for last few years (no dues on property tax). When I tried to check the process of getting the name transferred from my parents name to my name, I came to know the property is showing under somebody else name (in Tahshildar office). Where as the property tax from Nagar Nigam still comes on my father's name from years. My father made that house. Please help me with the process to get it transferred on my own name. Would that be possible by any chance, without letting third party know about this (as it seems they have done it illegally or by mistake the records are showing under their names, I am not sure.) It would be very helpful, if anyone of you can help or advice me on this.