Want to claim for my husband's share in property after his death

I am living in ghaziabad (NCR) and I want to claim my husband's share in his mother's property after his death which is in Hapur . Neither my father in law nor my mother in law is alive and no will was made by them. But my brother in law , who is living in it , denied to give my share and is doing construction on it without my consent. Please tell me the legal steps which I need to follow in order to claim my share. An immediate reply is needed. I'm in need of legal advice please reply as soon as possible..