Internet suddenly stopped working

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http://askubuntu.com – I was using NoMachine to access Ubuntu 11.10 when suddenly the internet on Ubuntu stopped working. Now Ubuntu doesn't recognize the internet at all (including locally). Symptoms: Doesn't recognize the fact that there is an ethernet cable attached. (I've tried switching cables, didn't work.) GUI says "No network devices available" Can't ping external IP addresses. Tried changing /etc/network/interfaces to eth1 instead of eth0 but it didn't work. ifconfig provides no output relating to eth0. When I type "/etc/init.d/networking restart" it tells me "Cannot find device 'eth0'/Failed to bring up ()