if you have x running, stop it and enter the shell.
then type, I believe you have to be root to run the command:
this will autoconfigure your xorg.conf file.
to test the settings, just type
X -config /root/xorg.conf.new
usually you will get the X server up and running, and can press CTRL+ALT+BACKSPACE to kill it.
if not, you will have to modify the config file. just play around with the xorg.conf.new until it works.
when it works, just type
cp /root/xorg.conf.new /etc/X11/xorg.conf
now you can reboot and the X server and your windowmanager should start