The new issue that you are having (Pixel Format Not Accelerated) is because of the fact that you rolled back your display drivers. (more info on Pixel Format Not Accelerated)

Once you've updated your drivers to the most recent version, you should try a clean-install of the launcher data.

This is done by following this simple steps:

1. Close the launcher. Go to this path in Windows:

2. Move out and back up anything you want to keep (such as your single-player worlds, screenshots, resourcepacks ect.)
3. Delete the entire contents of the folder (.minecraft). After this try opening the launcher again.