How can i claim my share in ancestral property

My Grand Father has 3 son;s and 2 daughter. Among them my father is elder and well educated among brothers. Earlier we lived together. But due to non-understanding we collapse. My both uncle live a luxury life. My uncle already sold some lands of my father by doing his fake signature ( which are part of my father ancestral property). But due to simplicity my father never restrict them. But whenever he ask for his share they ignore him. even we are not in joint family since last 15-20 years. My father is a simple man and show no courage to demand for his share in his father;s property. My grand father is now 95 years old. Both my uncle live a luxury life. I want justice. Kindly guide me how can i claim my share in my grand father property ( even if my father does not favour me). i know he want his share but with peace, which is not possible now as both uncle has complete hold on ancestral home and properties. And they are not interested to talk on this matter. Please guide me.