Registration of House in Own name after passing away of Father

Kindly advise me with regard to my below stated question: My Father passed away in the year 2009. He had purchased a 2 Bedroom Flat in Ghaziabad and leased it. Registry of the house was not done as my father passed away suddenly. He was a Govt Employee. Due to a fire in his office, while he was alive, the Documents of the house were destroyed. (My father intended to get the house registered so he had kept the documents in his office). My Mother also passed away in 2011. I am the only Child of my parents and also a govt employee. I need to register the House in my own name as soon as possible. Since I do not have the original documents, I have faced lot of difficulties with regard to registration of the house in my name. Can you please guide me about the proper procedure to apply for ownership of the house. I have the photocopy of Allotment letter(In my Fathers Name) and Original Handing/taking over certificate of the Flat (addressed to my father and Duly signed and stamped by Allotment Authority), with me. Will these documents be sufficient to apply for ownership of the house? Kindly advise me as to the procedure for registry of the house in my own name as well as succession certificate procedures, if required.