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.)
Try alternative urls such as fb.com
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 : firefox chrome internet explorer
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.
Clear your local DNS cache to make sure that you grab the most recent cache that your ISP has. For Windows - (Start > Command Prompt > type "ipconfig /flushdns" and hit enter). For details choose your operating system :
If you can access a website at office or from a 3G network yet it's not working on your computer, it is a good idea to use an alternative DNS service other than your ISPs. OpenDNS or Google Public DNS are both excellent and free public DNS services.
Check our help page for step-by-step instructions on configure dnshow to change your DNS.