If a domain has disappeared from the server’s IIS configuration, Plesk has included a tool that can be used to resync domain information, within the Plesk database, to the server’s IIS configuration.  You can use the following command to resync doman information between the Plesk database and IIS for a specific domain (replace yahoo.com with your domain name):

C:\Program Files\SWSoft\Plesk\admin\bin\websrvmng.exe —reconfigure-vhost —vhost-name=yahoo.com

After performing this command, the missing domain should have been readded to IIS. This tool can also be used to globally resync ALL domain configurations between the Plesk database and IIS. To do this, you will use the following command:

C:\Program Files\SWSoft\Plesk\admin\bin\websrvmng.exe —reconfigure-all