What's the link to your site? I can probably help.

That is good because I was going to say that your ip and domain isn't mapped correctly. Was going to use some tools to check ip and dns information. More than likely the domain is not setup to the right nameserver. That is why you cannot access it via domain name or ip address. It isn't being translated from www.domain.com to ip xxx.xxx.xxx.xxx That's what the job of the nameservers is to convert name to ip. Anytime you register a domain (or switch hosting companies), you have to make sure you have setup nameservers correctly with your domain registrar first.