I have been using 11.10 for a month or two, and I always had these icons at the top right (mail/messenger, battery state, volume control):
After upgrading to 12.04, I lost all of these tray entries except the time. After about 5 or 6 hours of wrangling, I found that I needed to reconfigure network settings in recovery mode and whitelist every program using the tray. I managed to do this, but it's only given me network strength, Dropbox, User Accounts menu and the top-right system menu.
This is all I really need for basic operation of the system, but since I'm used to having Banshee and all my messaging services up there, I'd really appreciate being able to revert to the old settings. I have read that I need to use "Add to panel" but I can't find a way to do this anywhere. If I do right-click, alt-right-click or windows-alt-right-click on the panel, nothing happens at all, so I can't access the menu that way. Anyone with any help would be welcomed. Thanks in advance.
EDIT: Ok, after fiddling with a whole lot of things and several reboots, the missing icons have reappeared. I think what probably did it was purging and re-installing alsa, but I have no idea why. I guess that solves my problem. Now I just need to fix my microphone!