Ubuntu 에서 그래픽 드라이버가 안잡힐 때.. 다시설치하는 법

in terminal write
sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade && sudo apt-get install build-essential && sudo apt-get install linux-source && sudo apt-get install linux-headers-generic 
sudo gedit /etc/default/grub #change line "GRUB_CMDLINE_LINUX_DEFAULT..."-line to 
GRUB_CMDLINE_LINUX_DEFAULT="nouveau.blacklist=1 quiet splash nomodeset" #(forces low-level graphics to ensure putty does not give black screen)
sudo update-grub2
sudo apt-get remove nvidia* && sudo apt-get autoremove #ensures no former installation clashes with new install
sudo reboot 

After reboot get correct nvidia-driver (chose graphic-card and OS) at “http://www.nvidia.com/Download/index.aspx?lang=en-us" (or search webb with “nvidia download”). Right-click on downloaded file and change if to executable. 
sudo gedit /etc/modprobe.d/blacklist.conf #add these lines at the end:
blacklist vga16fb
blacklist nouveau
blacklist rivafb
blacklist nvidiafb
blacklist rivatv
blacklist lbm-nouveua
options nouveau modeset=0
alias nouveau off
alias lbm-nouveau off 

Open a putty-terminal with Ctrl + Alt + F1 
sudo service lightdm stop #stops graphic session to enable nvidiainstallation
cd Downloads #(or wherever you downloaded your nvidia-file)
sudo ./{the downloadedfilename.run} #follow installation-instructions (normally yes to all)sudo nvidia-xconfig #(if you did not chose “yes” to this in the installation” 
sudo nano /etc/default/grub # change the "GRUB_CMBLINE_LINUX_DEFAULT..."-line to below:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset”
sudo update-grub2 #update grub!
sudo reboot

출처 : http://ubuntuforums.org/showthread.php?t=2263316