After running out of battery in Kubuntu 10.04 my laptop didn't shutdown propertly and lost all network connectivity (Wired and Wireless). The KNetworkManager in the taskbar told me that it was disabled and when I ran this command:
sudo lshw -C network
All the network interfaces appear disabled.
The solution was stopping the network manager:
sudo service network-manager stop
and removing the file that store the state of the network manager:
sudo rm /var/lib/NetworkManager/NetworkManager.state
After that reboot the pc and the network manager should work again.