I am posting this question from my Windows desktop, because as of this morning my laptop is no longer even an internet accessible device, and doesn't even seem to think it's supposed to be an internet accessible device.
My OS is Ubuntu 14.04, 64 bit. The laptop is an Asus X551CA, and I got it in 2013 April.
Last night, I installed a routine Ubuntu update. I then restarted my computer. This morning, I have no internet. Like, at all. When I open up Firefox, every single tab says it failed to load the requested page. At the top right corner of the screen, there isn't even an internet icon. I tried connecting my ethernet cable, but it didn't even react at all.
I tried restarting like three or four times. It doesn't help. The internet is still missing.
I tried the following terminal commands, as suggested by responders to this question.
sudo service networking restart sudo service networking force-reload sudo dhclient sudo apt-get update
Each one returned errors.
The first one returned this.
stop: Job failed while stopping start: Job is already running: networking
The second one returned this.
reload: Job is not running: networking
The third one returned this.
And the fourth one, after spitting out a large wall of text, then returned this.
W: GPG error: http://deb.opera.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 63F7D4AFF6D61D45
I have no idea what to do. It's the very end of the semester, and I have a research project that I need to complete by the end of monday. So it is, to say the least, absolutely imperative that my internet be working soon. Please, please help.