I am running 12.04 LTS alongside Windows 7. When I boot into Ubuntu, it says that there is no firmware for a wireless network, and it shows "no wireless network" and I can't connect to the Internet. When I boot into Windows, it works fine.
How can I get it to work because I obviously need to be able to connect to the Internet for Ubuntu to be useful?
You didn't specify what device it is for, but generally speaking, you should try these things first:
Make sure you've enabled multiverse repository (see How do I enable the "multiverse" repository?) and install these two packages: linux-firmware 
and linux-firmware-nonfree with your favourite package manager.
It should provide the firmware files you need.
The drivers and/or firmware aren't shipped with Ubuntu by default due to licensing issues.
