Change father's name

A family friend of ours used to take care of my education and other concerns of mine, with my parents' approval . He was and is childless and he had an idea of legally adopting me as his daughter. Because of this, he gave his name as father's name in school records and his name has remained in all the records (Aadhhaar, Voter ID, passport, school and college certificates etc.) until now. However, a legal adoption never happened and the idea was dropped as other members of his family were perhaps against it, or for some other unknown reasons. Both my parents are deceased and I have no siblings. I do not want his name on any of my records and want to change the father's name from his to my biological father's name. 1. How can I legally affect this change in the records of all the concerned educational and civil authorities? 2. The only record I have which bears the name of my biological father is my birth certificate. Would this document alone be enough to institute a legal procedure? 3. Would the legal procedure require the sworn testimony of any related persons? I must say I have no person (relatives or neighbours) who would be willing to testify to my identity in a civil court. Kindly help. Vidya V.S