I have problems with wowhead atm too. I can enter it, but I only get the logo and the search bar, no menus. If I search for anything I just get a blank page with no results. I thought it was because of running adblock/noscript but the same thing happens in 4 different browsers with no plugins installed and even on another computer. Works fine on my phone though.
Assuming it looks like this, one of the JS or CSS files isn't loading properly from their CDN. Need to clear your cache / try different browsers or just wait for it to start working again. See this thread when you can access it again.