The very first thing to do in such a case is to try another device (a Mac, a tablet, a PC, a laptop, an iPod, a phone, whatever you have). Then you would have noticed it that site doesn't work there either. So something is wrong with that site, not with your Mac.
Just wait until they fix it. And maybe it's gone forever. That happens also.
I'm using an Apple Mac, and the last time I used it, I reset all of the internet settings for each of my browsers, as well as my flashplayer settings.
Today, I can go on every single website except from:
And this applies for all browsers
As soon as I click on the link, it will not load.