Wireless shows up as disabled, how can I get it working?

It is likely that the network-manager state got corrupted. Open the file /var/lib/NetworkManager/NetworkManager.state. It should look something like this:

[main]
NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=true

Change any from 'false' to 'true' to re-enable networking. It may work better if you first stop NetworkManager:

sudo stop network-manager

And start it again once done.. Or reboot

This happened occasionally after wakeup in Lucid. In Maverick this should be fixed.

Try this:

• Install rfkill -> sudo apt-get install rfkill
• Give this command in terminal -> rfkill unblock all

Your wireless will work instantly, I hope. I guess you have a Intel wireless card and an Hp laptop, one of them at least.

On my Acer 3500 running ubuntu 10.10 the wireless suddenly stopped working after a screwy suspend/hibernation/power-off event. No amount of reboots would renable it. rfkill said the wireless was turned off at the switch, though the light indicating the wireless card is turned on remained on. rfkill unblock all had no effect.

$ rfkill list
0: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes

Network manager indicator said "wireless disabled" instead of "device not ready" as in the question. It was greyed out and not possible to change it to enabled. After a couple hours of troubleshooting and research I finally discovered the solution (for me):

sudo rm /dev/rfkill && sudo reboot

Kudos to Philip K. Adetiloye for taking the time to write about in Ubuntu Wireless disabled: SIOCSIFFLAGS: Operation not permitted. (The error message refers to the output of sudo ifconfig wlan0 up when /dev/rfkill is in the broken state.)