Did the proxy site you were using get blocked? Try out some of the sites listed here. They were submitted recently, so they're likely to be accessible. Stay on top of the latest updates, videos and posts on your favorite sites, like Facebook and YouTube, by staying ahead of your IT department and using a proxy they haven't blocked yet.
If you lose access, just come back and try another one, or you can check out some of the sites listed on our popular proxies page.