Wireless stopped working ...

Out of the blue, wireless networking stopped working on our Dell Inspiron 1440. It runs Ubuntu 10.04 LTS, and no system update was performed before things stopped working. The Network Manager menu in Gnome shows Wireless Network Disabled, and Wired Network as Disconnected. Meanwhile other laptops in the house have no problem connecting to the wireless network, so this must be something local to this laptop.

In digging through Network Manager, iwconfig, iwlist, wpa_supplicant and friends, all I could come up with was that /var/lib/NetworkManager/NetworkManager.state lists WirelessEnabled=False. Manually setting this to True and restarting NetworkManager gets us plenty of log messages that show the device exists, and then gets disabled.

Finally, I realized that someone must have pressed the Disable Wireless button on the keyboard. Pressing it again resolved the problem. Sometimes it's the simple things ...