I just tried to switch to the nouveau driver (from Nvidia proprietary) on my Ubuntu 14.04 machine, and now I can't access anything. When I start the computer I hear the drumroll when I reach the login screen, but all I see is some weird test screen (squares in different colors, changes every few seconds).
ctrl+alt+fx doesn't work, so I have no way to get a tty. I'm currently writing this from a live usb.
Is there some way for me to change the driver if all I have access to is the filesystem (from the live usb)? Or am I totally screwed?