I locked my screen for a moment and now I am unable to login back into my Ubuntu 14.04 machine, not even in a "Guest Session". After a moment of panic, I realized that I am the responsible, as I think I executed the following (I'm 99% sure) a moment ago:
sudo chmod 555 /etc/shadow
Is there a way I can restore the original permissions of
/etc/shadow (with an Ubuntu live CD maybe?). I'm also 99% sure no other files were modified in my moment of stupidity.