Hi @tique

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I grasp that the notebook came with Ubuntu and you have now installed Windows 7.  You have tried installing graphic drivers  with no success.

Here is a link to the recommended software and drivers for your notebook. 

HP Pavilion g6-2238tx Driver and Downloads 

I would delete the drivers that you have previously tried to install.

Restart your notebook.

Go to download page   and choose the "check now" option.

This will allow it to scan your system and create a list of recommended updates and  HP software for your system.

If the issue remains please contact HP support for assistance.

Contact HP Support

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Good Luck!