I'm such a n00b here's what I did...

I have Debian installed, and I use the KDE desktop. Everything was working fine, but I saw the 3D desktop program XGL and I tried to compile and install it. I ran a setup script, but apparently the script was not for Debian.

Now everytime I start Debian, Xserver cannot start because of an error in '/usr/X11R6/bin/X' because a file 'libx.au.06' or something similar does not exist. Basically, I want to have everything back the way it was before I installed this stupid script.

This is the script I ran:

http://sonique54.free.fr/xgl/setupxglen.sh

What can I do from the shell since I have no GUI anymore, to fix this instead of completely reinstalling the distro?

There's a couple things to try:

1) I would do is go to /etc/X11/ directory (cd /etc/X11/). See if there is a file xorg.conf.old (or XF86Config-4.old for Sarge). It might be .0 or .bk or something else. You're basically looking to see if the script made a backup file. If there is one, you can try changing to root by su and enter password. Then do cp xorg.conf.old xorg.conf (adjust the filenames accordingly).

2) Try su to change to root. Then run dpkg-reconfigure xserver-xorg (or xserver-xfree86 for Sarge).

After each of those, do /etc/init.d/kdm restart as the root user to restart the x-server. Be CAREFUL when you are root! You have become all powerful! You can seriously hose your system!

You've been warned...