Reseting Gnome Settings

If your gnome-panel corrupt , Application Menu, Places Menu and System Menu and some other menu items will disappear.
How to recover it

Boot the system upto Login Window. Press Ctrl + Alt+F1

Now You will get a Text based login screen

login with your username and password

now you will get a $ prompt.

The default menu application in Ubuntu is functional, but it is also down to earth basic. GnoMenu tries to replicate the looks and functionality of KDE's Menu application. And I have to say, it almost does. GnoMenu comes with a number of themes and a easy to use configuration menu.

The Ubuntu menu can be customized so that it fits your needs and gives you access to what's important while not displaying menu items you'll never need. I've created a 'Customize The Ubuntu Menu' video and placed it on Youtube and at the end of this Ubuntu tutorial.

The Global Menu for Ubuntu Netbook Edition 10.10 has just been uploaded to a PPA. The new "global menu" is called "Application Menu" and it can be installed in Ubuntu 10.04 Lucid Lynx already (both in GNOME and KDE). Here's how.

GNOME Shell 2.31.2 was released yesterday, bringing some exiting new features such as support for inline chatting in the IM notifications which now use Telepathy, an initial application menu in the top panel (for the moment it only holds a "Quit" option), restyle user status menu to match application menu and many others.

(Not yet a package, but still interesting enough to tell and hey: bleeding edge.) Circular Application Menu for Gnome is a Google Code hosted project providing a different access method to your Gnome menu. Actually all it does, is displaying the menu as circles:

GnoMenu - A consolidated menu for gnome that brings eye candy to the world of the Gnome menu’s. Fully functional menu , supports themes , for a composited or non composited desktop. It can emulate the look and feel of the most beautiful menus of most modern desktops, and it can also use custom menus, due to its powerful theme XML engine.

The Gnome2 GlobalMenu project is an attempt to produce a GTK module and panel applet for gnome2 that acts as a global public menu for all gtk-powered applications. Instead of the application menu appearing on the actual window below the window manager "bar" it always appears on the panel.

Here's the bug I filed in Launchpad for the misbehaving Me Menu in Ubuntu Lucid: Social bar in Me Menu only shows up when I add an account to Gwibber, the next day it doesn't appear (The Me Menu Bugs - Bug #576688)