Restore Panels back to Default Configuration in Gnome..

Many times due to some mis-click or other reasons, we find that some essential Applet has gone missing from our Desktop panel. Once removed, it is hard to place them back as we don't know where to find them. So, here is an easy method to get the panel back with DEFAULT SETTINGS.
Be careful, because it will remove all the settings you have made to the panel in order to customize it and bring it to default. You will have to reconfigure it according to your needs.
Open the Terminal window and enter the following command at the prompt:

gconftool-2 --shutdown

(Note: There should be no spaces between the two dashes before shutdown.)

gconftool-2 -recursive-unset /apps/panel


Then enter the next command:

rm -rf ~/.gconf/apps/panel

And enter one more command:

pkill gnome-panel

That's it!

Both top and bottom panels will appear (if missing) with their default settings. Now you can customize them to your preference and get on with using Ubuntu.