Or showing something like ‘No public twitter messages’? It’s probably because Twitter have recently changed the method used for third party sites and plugins to display tweets inline and your site code is using the old method which has now been discontinued.
The solution is to…
a) change plugins if you’re using an older plugin – for say WordPress – such as ‘Twitter for wordpress‘ which hasn’t been updated for a couple of years. This might involve some restyling of CSS elements for your theme. b) If it’s a built in component you’ll need to go under the hood and look for the twitter call code.
basically you need to be looking for the code in your widgets/plugins/shortcodes that looks something like this:
http://twitter.com/statuses/user_timeline/username.json
?callback=twitterCallback2&count=5
that’s the old API method.
it needs to be changed to something like:
http://api.twitter.com/1/statuses/
user_timeline.json?screen_name=username&include_rts=true
&count=5&callback=twitterCallback2
see also:
http://support.designerthemes.com/forum/topic/1832/twitter-feed-stopped-working