Hi,

For the duplicate Class 10th marksheet you will have to follow the given steps:

Fill the application form for duplicate certificate

Prepare DD of IPO for the amount you will have to pay to get the certificate.

Attach Identification certificate by principal of your school

You will also have to attach press release (new paper declaration)

After this, Send the form to CBSE regional office with attachments.

Here is a link which can help you better to understand this: https://www.cbse.gov.in/faq/MM%202016%20Duplicate%20Form.pdf

I hope this helped you.