If your Pidgin is failing to connect to yahoo recently, dont worry, you are not alone. This was due to discontinued support to Yahoo protocol 16. Check pidgin changelog for more info. You need not worry about this problem. All you have to do is to upgrade your version of Pidgin to the latest edition Pidgin 2.5.7.

Get the public key for Launchpad PPA for Pidgin

• Simply go to Applications > Accessories > Terminal and type the following.

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 67265eb522bdd6b1c69e66ed7fb8bee0a1f196a8

Add Pidgin Launchpad Repo

• Goto System > Administration > Software Sources and select Third Party Software tab. Now click the Add button and enter the repo address given below.

 deb http://ppa.launchpad.net/pidgin-developers/ppa/ubuntu jaunty main

Upgrade to Pidgin 2.5.7

• Simply do the following in terminal.

       sudo apt-get update
       sudo apt-get upgrade