All networking disapearered and usb is not working [how to fix]

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http://www.kubuntuforums.net – Restarted my main PC yesterday and then network-manager, network-manager-kde and plasma-widget-networkmanagement are suddenly missing. No big deal I thought; I'll just download the packages with : cd /home/my-username sudo apt-get download network-manager network-manager-kde plasma-widget-networkmanagement Then I copy the debs to a usb drive and install on the offline computer. But then I discover that USB isn't working either. Seems to me, that my only option is to reinstall. Any thoughts? (HowTos)