If the site is UP but you cant access the page, try one of the below solutions:

Browser Related Problems

Force a full refresh for the site. This can be achieved by pressing CTRL + F5 keys at the same time on your favourite browser (Firefox, Chrome, Explorer, etc.)

Clear the temporary cache and cookies on your browser to make sure that you have the most recent version of the web page. For instructions choose your browser :   

Fix DNS Problems

A Domain Name System (DNS) allows a site IP address (192.168.x.x) to be identified with words (*.com) in order to be remembered more easily, like a phonebook for websites. This service is usually provided by your ISP.