The common url for Kickass Torrents website http://kat.ph seems to be down. There is an article on Torrentfreak discussing the situation.
A few moments ago KickassTorrents disappeared from the Internet prompting the usual flurry of worried emails. While these instances of downtime are usually down to minor technical issues that tend to sort themselves out, there are signs that something a little more serious might be underway. Details are sketchy but at the moment it appears that the site’s KAT.ph domain is being replaced with a new one, KickAss.to.
Source: http://torrentfreak.com/kat-ph-goes-down-following-domain-issues-switches-to-kickass-to-130613/
You can still get to Kickass Torrents by going to their backup domain name: http://kickass.to/
So fret not, just point your web browser to their backup domain name kickass.to for now, and keep an eye on up to date Torrent news over on TorrentFreak