Ubuntu - no wireless extensions
If you are using ubuntu and you have enabled wireless network, your wireless is working fine for other devices but ubuntu does not show wireless connections.
If you run command iwconfig in terminal and it shows no wireless extensions.
Here is solution for you.
Install following packages in your ubuntu. Run the command in terminal.
$ sudo apt-get install b43-fwcutter firmware-b43-installer
Restart ubuntu. Now you should be able to see wireless connections in notification area.
Run command iwconfig.
Note : Check if a wireless card has been implemented in your system.
# lspci | grep "Network controller"
If there is no output, it means it is not implemented yet.