In Sony vaio my NVIDIA GeForce 8400M GT not working after vista 64bit upgrade

I had gone with Windows Vista upgrade for Sony Vaio VGN-FZ11Z laptop. I had upgraded to Windows Vista Ultimate. It came with Windows Vista Home Premium. After upgrade I am getting issue while playing games. It has a NVIDIA GeForce 8400M GT graphics card. It went black at the time of playing game. I restarted tge system but still the issue is same. Sometime there is a black screen and dotted vertical lines. The system freeze at that point. I had gone with restore also also still it is not working. This is a driver issue. How to fix the same.

Usually when you upgrade Windows is able to store the existing drivers. They are not wiped out. I had updated to a higher version of Windows Vista in similar may and in my case everything is working fine. Run Windows Update. You might get all the required driver updates through that. Go in Device Manager and checkout the list of all pending hardware to be installed. Add them one by one. You can find the drivers on the official website of your laptops manufacturer.

Windows Update might help you. But if that fails then you can get the drivers manually. It is very important to have proper drivers or else your system might crash with bluescreen. The first thing you must do is wipe out all existing drivers and unwanted software from your system. The second option you must try is download the drivers and add the manually. And keep a backup of all the files with you.