Gnome Shell is the new core user interface for Gnome 3 which provides switching windows and applications but you've probably already heard of it by now so I'll skip the introduction.

GNOME 3.8 has been released today, the new version bringing many new features and enhancements, including a new application view and overhauled window layout for GNOME Shell, new setting panels for privacy, search and notifications and of course, many updates to the core GNOME apps like Web (Epiphany), Boxes, Documents and more.

Let's take a look at what's new!

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.

Cardapio can work in two modes: as a panel applet (in which case it is an alternative to Gnome's application menu applet) or as a stand-alone launcher (in which case it is an alternative to the simplest use-cases of Gnome Do). It has a beautiful gtk-native interface and includes plugins for performing inline searches of Files (via Tracker), Software Center, Google, Wikipedia, and much more!

(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:

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.

This tutorial will explain how to recover disappeared Application Menu, Places Menu and System Menu in ubuntu
Procedure to follow...

This is a circular-application-menu (C-A-M) prototype mirroring the same structure as the existing application menu for the GNOME desktop. This was originally just a paper prototype which I did back in March 2007, and decided to code over Christmas 2007-2008.

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.