|Make sure it is not in your Hosts file, or Restricted Sites (IE).|
You can check out hosts file by temporarily disabling it. Follow the path:
I suggest you change it from hosts to hostsx, close IE then open it and try the website again. If it doesn't help rename it back again. If it does help we will need to look at the content of your hosts file.
Restricted Sites is here:
Internet Explorer > Tools > Internet Options > Security tab, Restricted Sites icon
>Sites button. Look down the list for it and remove it if you find it.
Sometimes a virus can block things but if that is the only problem you are having it is unlikely.
Always pop back and let us know the outcome - thanks