1. Well, since the gift deed was executed after the Will , the Will shall have no force in the eye of law.
2. Now if the gift deed was fall out of force, coercion or fraud then the same is void for which you can file a suit for setting aside the gift deed .
3. Considering the mental derangement of the Donor you suit should be allowed and the gift deed should be set aside in which case even if the Will is destroyed the law of Inheritance would take force.