Error: device not ready(firmware missing) while enabling wi-fi ubuntu 12.04

When I tried to enable wi-fi on my laptop, a ubuntu 12.04 system,
I got the following Error: 
device not ready(firmware missing)

To solve this, first check if wireless driver is installed in your system.
Check for wireless driver in the following path:
Applications-> System Tools-> System settings->Additional Driver

If it is present and activate it.

If not, we need to install the driver. Use the following commands for the same and you are done! 
$ sudo apt-get install firmware-b43-installer
$ sudo apt-get install firmware-b43-lpphy-installer  

Reference:

http://askubuntu.com/questions/149999/how-do-i-install-missing-firmware