"Wireless Device not managed" in ubuntu 9.10

Sometimes while updating some packages or installing conflicting application in ubuntu 9.10 cause wireless device problem. And in the network icon "device not managed" error is shown.
Today i installed 'xnetconfig' and after configuring network device wireless network card stopped working. To solve this issue we need to edit nm-system-settings.cong file in /etc/NetworkManager folder in root directory. You must be logged in as root to edit that file. You need to just set value 'true' instead of 'false'

 

After this just restart network manager by using following commands

sudo /etc/init.d/network-manager restart
sudo /etc/init.d/networking restart

Now the wireless device should work properly.