Clarification on share of son in father's property

Hi, my father expired dt.01.July.16 without leaving any Will (Hindu). He survived with my mother, myself, my younger brother. We got a Succession Certificate from SDM office (Rampura, Delhi) in which all 3 names are mentioned. My father left a 100 sq yard house of 2 storey at Hari Nagar, Delhi and now my mother and my younger brother are not willing to give my share in it. I want to understand legally am i eligible to have my share within the house and if yes, how can i proceed and to whom to approach. Also, my mother and brother are additionally claiming that they have a signed paper from my father which states that my father transferred house in my brother's name only however they are not showing the said paper to me. Thanks in advance.