How To Reset zone files
To reset your DNS zone files to the defaults that your hosting provider specifies, perform the following steps:
1 – Open cPanel (yourdomain/cpanel).
2 – Click on (Advanced Zone Editor) from Domains section.
3 – If this account owns more than one domain, select the domain that you wish to manage from the Domain menu.
4 – Click more.
5 – Select the Are you sure that you wish to erase all of your entries and revert to the default state? checkbox.
6 – Click Reset Zone File