Death certificate many years after death

you need to file for declaration in the CJM court

apply through online to this portal. www.services..india.gov.in "This service can be used to declare the non availability of a Death Certificate. An applicant can request for Non availability of Death certificate under the following circumstances. 1. Death was not officially recorded. 2. Death records are lost at the Dept during natural calamities."

You get first an endorsement from concerned authorities and file suit in local jurisdiction court and publish it in local paper as per court directions then court orders concerned authorities to register and to  issue  it.