To me it sounds like you left the xorg.conf file behind after uninstalling fglrx.
Lets get you back to a desktop first.
When the screen goes blank and just sits there press Ctrl+Alt+f2.
This will switch to a different tty login go ahead and login.
1) shutdown x server
2) make sure fglrx is gone
sudo service gdm stop
If you see any module files at this point that's bad. I don't believe you stated how you installed the driver from the web or Ubuntu.
sudo find / -name fglr*
Follow the purge directions at the link pme 72 posted https://wiki.ubuntu.com/X/Troublesho...thRadeonDriver
I perfer the
Problem: Need to fully remove -fglrx and reinstall -ati from scratch
If you follow it to that point you should be setup to use the open source driver again.
sudo /usr/share/ati/fglrx-uninstall.sh # (if it exists)
sudo apt-get remove --purge fglrx*
sudo apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon
sudo apt-get install xserver-xorg-video-ati
sudo apt-get install --reinstall libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core
sudo dpkg-reconfigure xserver-xorg
3) Now make sure the xorg.conf is gone.
4) Lastly make sure ati or radeon isn't blacklisted
sudo rm /etc/X11/xorg.conf
If you see radon or ati in this file remove/comment their entries save and close. If this file doesn't exist on your system(is blank) that's fine as well.
sudo nano /etc/modprobe.d/blacklist.conf
You should now be back to the open source driver and clear of any fglrx.