Hello,

In case you lost your 12th class leaving certificate, then contact your school from which you have completed your class 12th, you may need to show them some verification proof that you were the student of their school in class 12th, you may also need to tell some relevant information to them, and they will arrange the duplicate certificate for you.

Hope this helps, all the best.

You need to consult your respective college or institution itself as they might still be having the soft copy version of your leaving certificate so they can handle over to you the duplicate certificate of the same. That's the only option possible for now.

Thank you.