Q:

Recovering data after unity crash after installing radeon driver

I installed a graphics driver (for radeon in dell )  from ubuntu software center.  when the system restarted the sidebar is not appearing after login.  Before login at least few icons appear at top right.  After log in nothing appears & I cannot even open  terminal using "ctrl + alt + t".  Even the guest session does not work ! 
 When I tried "ctrl + alt + del" during boot to start in recovery mode, it still boots & this time the touchpad or mouse is not working. 
I should have not gambled since I recently migrated completely to Ubuntu overwriting Windows.  Is there a way to solve this problem or at least can I recover the data from the system; allowing me to reinstall the OS? 

A:

You should be able to press CTRL + ALT + F1 to get a virtual console and log in to recover data using the command prompt and fix your drivers.  To revert back to a GUI session siply press CTRL + ALT + F7.  Alternatively, you can get the grub menu by pressing shift while booting and the boot into recovery to get a command prompt.  
Once you have the command prompt you can remove the AMD drivers
sudo apt-get purge fglrx*

You can now reinstall xorg
sudo apt-get install --reinstall xserver-xorg

and then
sudo dpkg-reconfigure xserver-xorg

