How do you say that it was ancestral property which was sold by your father.
Property inherited upto 4 generations of male lineage (i.e., father, grand father, etc.) is called as ancestral property. The right to a share in such a property accrues by birth itself, unlike other forms of inheritance, where inheritance opens only on the death of the owner.
A grandchild does not have any birth right on the self- acquired property of his grandfather if it had been allotted to his father in a family partition in his capacity as legal heir and not as a coparcener under the Hindu Succession Act 1956.
Thus if you had mistaken your grandfather's proeprty for ancestral property then you may not have any rights in the property sold by your father, hence ascertain the facts and then approach a local advocate with all relevant papers for proper opinion on this