So, as of earlier today, Kubuntu decided to not behave and boots straight into tty (text-only) rather than giving me my GUI login.

That itself would not that much of a problem (because startx startkde gives me somewhat crippled GUI) if 'startx startkde' didn't require to be ran as root or sudo. Difference between the two options is that running as root gives me full root environment (say goodbye to running programs as <username>), while sudoing it as <username> configures desktop as if I logged with <username>, but every program runs as root by default, which is a) not so ideal and b) will force root configuration to the programs launched. Bypass exists, but is really fucked up. (New terminal window and su <username> && export $(dbus-launch)&&[program] - at least it's something.

This time, I actually do know what exactly happened before this happened.

I ran this script (switches xorg.conf file, useful for quick reconfiguration after connecting/disconnecting monitor). Script executed without any apparent problem, then KDM refused to restart. (Sometimes sudo restart kdm will restart KDM in an instant, sometimes I jump into tty1 and ran that line of code again.)
Well, actually it more hanged than restarted. And yes, I went to tty1 and restarted the KDM. After that, whole system froze (it didn't even react to ctrl-alt-Fx (Fx = F1, F2, ... , F12)) so I just restarted everything with holding the power button for 5 seconds. I haven't seen a login screen ever since.

TL;DR — how to force Kubuntu to boot in GUI mode?