Facebook chat had been changed long back with the introduction of the sidebar, after which they had introduced the sidebar ticker for a small period of time. You can also disable Facebook sidebar Ticker. A few hours back, Facebook has changed the entire interface and design by making changes to the News Feed and a few more options. But you still have an option to revert back to the old facebook design and this post explains how to get back the old facebook design/interface.
The current Facebook design looks like this:
I liked it and hence I would not switch back to old facebook interface but if you do not like it, here is how you can switch back:
Go to Account Settings->General
Click on the “Edit” link near the Language option.
Change your language to “English UK” is you are an English speaking person. You can change it to any other language except English US
Click on Save Changes.
Doing this will help you switch back to old facebook interface. But this is merely a temporary method and will not work when Facebook rolls out this new feature to other territories/languages which the social network supports.\
Update:The current method does not work out now as I had already mentioned, this is a temporary method. Facebook will be rolling out the new timeline to everyone and to get back the old facebook design you can install Fix New Facebook or Unf**k Facebook Scripts for Mozilla. Chrome users can add Facebook Classic Extension to get back the old Facebook interface.
You can also try by deactivating your Facebook account once and reactivate it again. I hope that helps but Facebook didn’t let me deactivate my account. Let me know if it works for you.