Individual applications set restore points in Microsoft Windows. Windows can also detect certain other changes and create points for you. These changes are backed up.
This, you already understand.
System Restore just brings them back to the point where you choose to restore.
Why did I say driver?
If you didnt restore early enough, then the driver may still be incorrect. In this case, uninstalling the driver would fix the problem since it would be redetected again.
Why did I say DirectX?
You recently installed a game, correct?
This upgraded the DirectX version.
If you restored again, the new version would be uninstalled, and it would render the game useless without the new version if the version it came with was required.