Pidgin doesn't show buddy list?

Check the value of the list_visible parameter in .purple/prefs.xml, if it is 0, close pidgin, edit and change it to 1, then restart pidgin.

<pref name='list_visible' type='bool' value='1'/>

You can also try the same with 'blist_autohide'

<pref name='blist_autohide' type='bool' value='1'/>

Faced the same problem. Completely reinstalling (purge and reinstall) pidgin and it's dependencies solved it for me. Try the following in a terminal.

Purge pidgin and its dependencies:

$ sudo apt-get purge pidgin pidgin-libnotify pidgin-data indicator-status-provider-pidgin

Clear stale archives:

$ sudo apt-get clean

Reboot.

Reinstall pidgin alongwith dependencies:

$ sudo apt-get install pidgin

This solved the issue for me. Pidgin now shows buddy list from indicator menu and when I launch Pidgin manually.