From:
http://www.binarytides.com/install-nvidia-drivers-ubuntu-14-04/
Find out your graphics card model
Use the lspci command to find out the model of your graphics card
$ lspci -vnn | grep -i VGA -A 12
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GT218 [GeForce 210] [10de:0a65] (rev a2) (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Device [1043:8416]
Here its GeForce 210
Find out the right driver version for your graphics card
Visit
http://www.nvidia.com/Download/index.aspx
Fill in the details about your graphics card and system and then click Search. On the next page, it should tell you the correct driver version with a download link and additional information.
For the above GeForce
? 210 card, it showed 331.67 as the correct driver which can be downloaded from the website. However we shall install the drivers from ppa to make things easier.