[SOLVED] Wireless Network Detected But Unable To Connect Under Ubuntu 12.04/11.10

If you can't connect to wifi networks and the buttons for connecting/enabling a wireless network are grayed out in your Network Manager indicator under Ubuntu 12.04 (Precise Pangolin) or Ubuntu 11.10 (Oneiric Ocelot), this means that your wireless network is disabled by hardware/software switch. This problem is common for users of laptops.

To check if there is a block on hardware/software of your wireless network, we need to run this command from the terminal:

rfkill list wlan

or

rfkill list all

Here are the outputs returned for my example:

~$ rfkill list all
1: phy1: Wireless LAN
Soft blocked: yes
Hard blocked: no

As you can see from the example above, I can't connect to the wireless network because software is blocked. To unblock it, you need to use one of these two commands:

rfkill unblock wlan

or

rfkill unblock all

Finally, restart your network manager with this command:

sudo service network-manager restart

You can now connect smoothly to WiFi networks.