Birth certificate

One option is to approach the municipality where he was born, mention the date you believe to be the DOB and request them to check for records. If date was not registered in their database for five years before or after the said date, they will have to issue a non-availability certificate. You should then attach affidavits of adopted parents and witnesses if any and use thone to substitute birth certificate. In foreign countries that is accepted. Another option is to hire services of a lawyer who can get a court order for declaration of date of birth using witnesses, evidences etc. That order shall serve as the birth certificate. Good luck.

You have been advised well as above.

 

Try from biological parents.

Inquire where he was born.

Obtain record.

 

Rightly guided. Getting court order of declaration seems likely option.