Modifying your screen resolution
Follow @ggarronYesterday after an upgrade of my Debian system the resolution of my screen switched to 800x600, I checked my xorg.conf configuration and everything was OK, but fortunately in Linux everything has an easy solution, what I needed to do was:
dpkg-reconfigure xserver-xorg
and Debian took care of the configurations, after that the option 1024x768 appeared again in my Gnome options.