Ok, so you seem to have created a website in ispconfig that uses the same domain name that you manually configured in the ispconfig vhost as exclusive domain for ISPConfig or you added some redirects that must override the manually altered ispconfig vhost or using wildcards or wildcard subdomains to override the ispconfig vhost. The result must be that ispconfig becomes inaccessible as any other software or website would become inaccessible if you do not use a dedicated port or domain/subdomain. In the same way you accessed it before. This depends on how you manually altered things as your setup is in no way a normal or standard ISPConfig setup anymore. You should really consider this as all the trouble you have now is not related to ISPConfig in any way, its solely caused by your manual changes in how the server is set up.