It appears to be something wrong with our DNS settings. I've changed my DNS address manually on my internet gateway/router thing. That fixed the problem. If you are unable to do so, then you might call your tech support and ask them to set you DNS to a different server, which should set things straight.
Here is the address for bps.lk, but I don't think it'll help to punch it into your address bar.
If you can change your own DNS server address, then you can find an alternative here:http://www.dnsserverlist.org/
The servers this page suggested to me appear to work.