Edit DNS Record

I have a domain name that has a custom mx record.


It has stopped working, mail gets rejected now with the error:



The response was:

DNS Error: 14320724 DNS type 'mx' lookup of <myprivatedomaincom> responded with code NXDOMAIN Domain name not found: <myprivatedomain.com>



When I view my DNS settings the MX record is in there but with a  (Priority: 0) setting.


There doesn't seem to be any way to edit/add the DNS records as per the support pages: https://uk.godaddy.com/help/delete-dns-records-19210?


Does (Priority: 0) mean it is now disabled?


How to I edit this setting?