15.04 Installed fglrx AMD/ATI drivers -- won't boot

I installed the proprietary AMD/ATI drivers on Ubuntu 15.04 64-bit, and restarted my PC. Now, it will show the Ubuntu logo, but won't go to the login screen. I can't switch to a terminal via CTRL+ALT+F1, CTRL+ALT+F2, etc.

I'm unsure how to uninstall the fglrx drivers if I can't boot to the login screen or terminal.

Running Ubuntu GNOME 15.04 64-bit w/ GNOME 3.14 on Acer Aspire laptop (model 8943G-9319, ATI Mobility Radeon HD5850)

Thanks in advance!

Thanks to the community, I found - and am writing down - the steps to remove fglrx AMD/ATI drivers when you can't get to the login screen (or a terminal/console/command prompt/etc.)

1. Switch on your computer. Wait until the BIOS has finished loading, or has almost finished. (During this time you will probably see a logo of your computer manufacturer.) Quickly press and hold the Shift key, which will bring up the GNU GRUB menu. (If you see the Ubuntu logo, you've missed the point where you can enter the GRUB menu.)

2. Select the line which starts with "Advanced options".

3. Select the line ending with "(recovery mode)", probably the second line, something like: "Ubuntu GNU/Linux, with Linux 3.8.0-26-generic (recovery mode)"

4. Press Return and your machine will begin the boot process.

5. After a few moments, your workstation should display a menu with a number of options. One of the options (you may need to scroll down to the bottom of the list) will be "Drop to root shell prompt". Press Return with this option highlighted.

6. The root partition is mounted read-only. To mount it read/write, enter the command:

   mount -o remount,rw /
   

7. If you have /home, /boot, /tmp, or any other mount point on a separate partition, you can mount them with the command (unsure if this step is needed, but unless I'm corrected by someone, I recommend you type in this command as well, otherwise you may not be able to uninstall fglrx. And, again, the command:

   mount --all
   

8. Type in the following command:

   sudo apt-get remove fglrx-*
   

   Enter Y to accept the changes. Ubuntu should then uninstall all fglrx drivers.

9. Remove the X.org configuratiuon:

   sudo rm /etc/X11/xorg.conf
   

10. Type in the following command to reboot your PC:

    sudo reboot
    

Ubuntu should now reboot and use the default open-source drivers again. Cheers!