I tried for several times installing proper driver by choosing from additional driver. But for each time I encounter with a dark screen. At last i decided to install it through Nvidia.run file. I've tried these steps
----Save the .run file in your home folder. This should have the path /home/YOURUSERNAME. You can get to this from Places->Home Folder. Press Ctrl+Alt+F1. This should bring up a text mode command line interface. Log in by first entering your user name then your password. Note that when you enter your password you will not see the letters of your password appear on the screen while you type. This is normal and is done for security reasons. Once logged in, enter the following commands by typing them in, then pressing enter:
sudo /etc/init.d/gdm stop
sudo chmod +x NVIDIA-Linux-x86-185.18.36-pkg1.run
Wait for the installer to finish then enter this command: sudo /etc/init.d/gdm start. This should bring back the graphical interface.
I'm not entirely sure if this step is required and, to be honest, I don't know what it does but when I installed the driver I opened a terminal Applications->Accessories->Terminal and entered this command: sudo nvidia-xconfig --add-argb-glx-visuals. This enabled me to enable visual effects. -----
In login I welcomed by a monitor error which it can't find a compatible one. I really feel failing in ubuntu.