today I've made the biggest mistake in my life: I tried to install a nvidia driver by running the .run file in a terminal. The driver setup asked me that there was a problem preventing the driver from being installed which could sometimes be solved by generating some kind of config file. I agreed and the config file was created, however immediately after that the installation terminated because of some other stuff I did not want to read anymore.
I assumed that this little incident did not affect my well-running system, but at the next bootup, I saw that I've been wrong. Ubuntu booted into a low-resolution mode and was finally stuck on a black screen. So I rebooted in recovery mode, went into root terminal, gained write access to my drive and tried to sudo dpkg-reconfigure xserver-xorg, which terminated without displaying any message.
I also tried to boot into low-graphics mode and start the graphics repair option which did nothing but showing me the option screen again and again.
How can I reset my display driver to default post-installation settings?