Yahoo! Messenger public chat rooms were discontinued on December 14, 2012
Resolution
In order to better focus on providing great new features for Yahoo! Messenger, we discontinued some Messenger services, including public chat rooms, on December 14, 2012.
We know that some long-term Yahoo! Messenger customers enjoyed these topic-based communities. However, we feel that by embracing the modern technologies and platforms available today, Yahoo! will be able to uncover better ways to foster meaningful communities and connections for our customers to use to connect with the people they care about.