How do I re-install Network Manager without an internet connection?

In case you only removed just Network Manager with the Software Center it is quite easy to reinstall by downloading only 2 packages from another machine connected to the internet:

• Using packages.ubuntu.com, download the network-manager package from a software mirror close to you. Take care to choose the appropriate architecture (amd64 for 64-bit, i386 for 32-bit), and release version of your installed OS.
• Download network-manager-gnome package likewise (am64 or i386).
• copy both files on your spare USB pen drive and take it to the broken machine.
  ^{(e.g. network-manager-gnome_0.8xxx.deb and network-manager_0.8xxx.deb)}
• Install network-manager and network-manager-gnome simply by double-clicking on these two .deb files. This opens the Ubuntu Software Center or Gdebi for reinstallation.
• After a reboot (or just logging out and logging back in) the network manager will run and uses your previous settings as before.

Note: This was not tested for the case when network-manager was removed in other ways, and if other applications were removed that may have deleted additional dependencies.

The following describes how to establish a wireless network connection via command line utilities.

I think this is a better option because it gives you the useful ability to interface with relevant command line utilities.

1. Use ifconfig -a to identify your wireless card. From hence forward, I will assume it's eth1.
2. sudo ifconfig eth1 up
3. iwlist eth1 scan to find available networks. iwlist eth1 scan | less if it's a long list.
4. sudo iwconfig eth1 essid [network] [key [pass]] Also, read man iwconfig to figure out how the wifi password is entered. You might also need to configure the channel and stuff.
   1. If you use WPA, wpa_supplicant will be necessary. http://ubuntuforums.org/showthread.php?t=263136
5. sudo dhclient eth1