If you mess us your Ubuntu panel, just like i did. Just Run the following commands.
ycsoftware@ycsoftware:~$ pkill gnome-panel ycsoftware@ycsoftware:~$ gconftool --recursive-unset /apps/panel ycsoftware@ycsoftware:~$ rm -rf ~/.gconf/apps/panel ycsoftware@ycsoftware:~$ pkill gnome-panel ycsoftware@ycsoftware:~$ gnome-panel &