my elder uncle dont want to give my share from grand fathers property.

Hi sir, my grand father has 4 sons.He died without distributing the property. Now my elder uncle want to abduct the entire share of my grand father's property without sharing my share with me. my father is the 2nd son, who died in 1990 and as I was minor that time, the property was under the capture of my uncles.Now when I am 25 yrs old and I am asking my share to them. They are refusing to give my share to me. My mother has not done any 2nd marriage. Please advise me that what can be done legally. My grand father has 2 wives, one died and one alive.