Have you ever had a SharePoint page "explode"? Odds are something from the server timed out. In the example below the CSS files never got loaded. The links timed out. A simple refresh should fix it. If it does, let your server admins know about the issue.
BTW, those weird looking icon collections are call image sprites.
If the refresh does not fix the problem, you may have a broken master page. (Have you been playing around with SharePoint Designer?) You can either use SharePoint Designer to select a working master page or edit your site's URL to take you to the Site Settings page and select one there..
http://yourServer/sites/yourSite/Pages/Default.aspx (or whatever your URL looks like)
to something like:
http://yourServer/sites/yourSite/_layouts/settings.aspx (2013 will redirect and add a "15" to the URL.)
From that page you can select another master page or make other changes to fix the issue. In some cases you even need to open SharePoint Designer to undo the change you made or to select another master page. For a publishing site click Master Pages in the Look and Feel section of the Site Settings page. If you see the following message then you do have a master page problem.
In some cases, just clicking OK and selecting the same master page will fix the problem. Otherwise, select Seattle or Oslo and see if that gets your site working again.