Answered on January 11,2019
I am assuming that you don't have birth certificate issued earlier and you also don't have your hospital records.In that case, you should get a Non Availability Certificate from the respective Authority. The Non-Availability Certificate is an acknowledgement or endorsement from the authority stating that the birth certificate is not available with them. Applicants have to fill a form and submit it to the authority, who will then verify the data and issue the acknowledgement.
You have to take this certificate and contact a lawyer. They'll ask you to bring your school passing certificate, voter ID card etc to prove that your Date of Birth as stated by you. A lawyer files an application in the court and after verification, a court order will be issued to issue you a birth certificate.