Claiming grandfathers property

My grandfather expired 5 years ago. My dad expired when I was 3yrs old. Mom expired 7yrs ago. My grandfather had 3 sons and 3 daughters. Off which only 1 daughters son is alive and 3. Son 1. Expired (not married/no legal heir) Son 2. Alive (with 1 son and 1 daughter) Son 3. (My father)- Not alive, My mother - Not alive. On death of my father in 90's my mom shifted to Mumbai along with me for good. Property of my grandfather is located in Chennai. Before his death, he called me up and told me that he has made a lot for me and kept since I'm an orphan. I only know about 1 property (I.e. my grandfather's house) Apart from the house I have no knowledge about the rest of the properties. 2yrs ago my grandfather's property was sold by son 2 and 3 daughters. I was not given any share in it. Though I feel after my mom and dad passed away I have a right in that property. Questions to the above case are as follows: 1. Do I have a share in the property? 2. If my mother or father has signed any NOC for not claiming the property before or after my grandfather's death ( Note:my mom dad passed away before my grandfather), do I still have a rightful share in the property? 3. If my aunties (3 daughters) have signed for sale of property and not taken any consideration in return, will the consideration be divided in 2 parts (my uncle I.e. son 2 and me) or will the property or consideration would be divided in 5 parts I.e. son 2, me and 3 daughters.? 4. How do I find out how many properties and assets my grandfather owned and which sold? 5. I do not have the address of any property as I was prohibited to meet my father's side family by my mother due to personal issues. So how do I go about with finding them or even get a title report for it as none of the people having a rightful share in it are co-operating with me on the same. 6. How do I go about in claiming my share in the property? Please guide step by step. Thanks. +917045296486 is my contact number for the same. I also need a lawyer from Chennai to do the needful for me after me getting a clear picture about this case.