My parents are almost 90 year and says they will give property to there daughter

Me and my younger brother have taken care of our parents since last 40 years ,I have worked very hard and gave my savings to my father to buy property,but as a indian son I told my father to register the property on his name , now my parents are saying that we have not done anything for them and they will not give us any property they even don't let their grandchild to stay in our house .they are saying they will give all the property to there daughter and her childrens . I really don't have any idea what to do now as from past 3 years we try to communicate with them but they refuse .some properties are of ansestors and some are bought by us on the name of the father, I do have bank records and evidence as my father is not working from past 50 years. Some times I feel they are mentally sick but I am not sure what is the problem with them. If there is any provision for this under law please guide us, me and my brother where forced to go out of the house which we made by so much hardwork.