There are a few reasons why your domain is no longer resolving. These include:

• your domain is not registered
• the domain has expired at the registry which you can confirm by contacting your domain registrar
• your domain could be suspended for some reason, including the new Whois Accuracy Program 

You can use the "Whois Is My DNS Provider" lookup tool to see if your domain name is present in the roots.

1. Your domain name may not have been brought over in The Great Migration
   It is possible your account or one or more or domains were not included in the data dumps we imported into the system. You can open a support ticket with "Missing Domains" in the subject line, include your missing domain(s), and if possible your old ZoneEdit userid and email address.
   
   
2. You were a legacy ZoneEdit reseller
   The legacy.zoneedit.com resellers channel was discontinued by the previous management in 2010. Please see this document on how we can possibly assist you in recovering your zone data from the now defunct legacy reseller channel.
   
   
3. There could be a problem with your DNS zone within the control panel.
   You can confirm this by logging into your control panel and clicking on CHECK under the TOOLS tab:

Check if there are any ERRORS at the top of the output:

If the output ends in OK, it is not a syntax problem within your zone.

• IF your domain is in the root servers (not expired, not suspended)
• IF your name servers are with ZoneEdit.com
• IF check tool output ends in "OK"
• IF you've checked the ZoneEdit Network Status and there is no system wide event (such as a DDoS) that could be impacting your zone and others
• Then you could open a support ticket (paid customers should use the premium support methods).