See if you have lost your certificate, then you have to atfirst file a complaint at your nearest PS and after that with the receipt copy of complaint you need to visit your school. There you will be provided forms through which you can get a duplicate certificate or you can provided some documents which you have to take to the regional education officer of your district and they will give you some date for the certificate. So you have to follow this and then the else you have to do as per the officials instructs you.

I hope this answer helps. All the very best for your future endeavors!