Society agreement (sales deed) is lost

Dear Sir, My Name is Mehul I live in Mumbai. I request you to guide me on the below matter. My Society agreement (sales deed) is lost. Earlier flat was registered on my father’s name however he was passed in 1998 and flat is now registered on my name as well as my wife name in 2007. Now I want to sell this flat and that time I come to know my Society agreement (sales deed) is missing and lost. I have original share certificate with me (on my name as well as my wife name), society maintenance bill comes on my name as well as my wife name, and society’s name plate is also on my name as well as my wife name. Now my question is: • How can I get sales agreement? Society said to me we don’t have your copy of sales agreement. Now what should I do? My society is registered in 15th December 1976 and in my share certificate name is registered on 25th June 1977. • What is the procedure to get duplicate sales deed? • Can I get copy of sales deed from society registrar office? • If I want to sell my flat buyer will get the loan on duplicate sales deed? • How can I come to know whether my father has paid the stamp duty and registration fees in 1977? My mobile number is 766074949. Please provide your valuable guidance Sir or please reply to this. Thank you.