So why would someone need this at the first place? When someone like me make a stupid mistake by removing them 🙂
Restoring volume icon is different in Ubuntu 9.10 or later versions.
So if you are in Ubuntu 9.04 or earlier,
1. Right click on the panel and click ‘Add to Panel’
2. Find Sound/Volume
3. Add it.
And if you are in Ubuntu 9.10 or later like me
1. Right click on the panel and click on Add to Panel
2. Find ‘Notification Area’ and add it. (IN case you have already have a notification area added like me, you can skip this step).
3. Right click near Notification Area
4. Find ‘Indicator Applet’ and add it.
By any chance if the above method does not work for you, you can restore your gnome panel by applying following commands in your terminal.
rm -f ~/.gconf/apps/panel
sudo /etc/init.d/gdm restart
Partial credit for this post: Ubuntu Forum 🙂
Let me know if you have any problem figuring this 🙂