Windows 7: Cannot change graphic card

Hi,
I have a samsung 3 series notebook. I have got a nvidia gt520 graphic card but i don't
know how but it stopped working and the intel hd is currently in use with which i cannot play games. when i went to device manager and updated the 3D video controller. It told that NVIDIA GEFORCE graphic card had installed and asks me to restart the computer.
When i do, it becomes black and shows "There is some change in the windows hardware
which has caused the computer not start". Below that there are two options- Launch
startup repair and another start windows normally. When i click on start windows normally the same page is displayed. when i select launch startup repair. a dialog opens and asks me to restore the computer to an older period of time. When i do the graphic card is again reverted back to intel hd graphics.
PLEASE HELP ME!!!!

Sounds like you have need the Optimus drivers (for Intel/nVidia switchable graphics).

If you can download such from Samsung, give them a try.

I'd look for a link, but you haven't supplied enough information.

Can you tell me what more information should I supply.

The exact model number, which should be sufficient to look up drivers online.

thank u for ur comments