Can i ask my share in my grandfather's property in uncle's possession?

First note that in order to clarify your doubts with regard to nature of the property in question if it is Ancestral Hindu Family Property or Self Acquired Property of your Grand Father. 

If the property of the grand father was his self acquired property then this property shall devolve to all his legal heir, if he died intestate i.e. no testamentary document such as 'will' exist with regard to the property made by him during his life time then property will be divided among the legal heir.

If the property is ancestral property then you have a legal right to claim your share. Assuming you are a Hindu, the division of property or partition will be governed by Hindu  Succession Act, 1956. As per the said act, you can file a suit of partition and application of injunction whereby seeking relief against all of them for interfering in right to enjoyment of property share in the ancestral property or even use this property for the purpose of family benefits only & not for his personal purpose. 

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