upgraded to windows 10 then downgraded back to windows 7

[The Blobfish]

upgraded to windows 10 and my CPU broke, downgrade to windows 7 and the divers for my graphics card won't install.
"This NVIDIA graphics driver is not compatible with the version of windows
This graphics driver could not find compatible graphics hardware."
and now I'm not able to re-upgrade to windows 10.

 

[NerdIT]

Do you have integrated/on-board graphics? If so, I would do a complete uninstall of the nVidia drivers using Guru3D's DDU program:

http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

Then, I would remove the card, and boot into windows with onboard graphics, ensure this driver is up to date. Reboot to ensure functionality (make sure the legacy CSM/Secure Boot settings in BIOS allow you to boot to older OS's while your at it)

I would then do a registry wipe using a tool such as CCleaner (free version):

https://www.piriform.com/ccleaner/download

Then I would reboot one more time, then shutdown, re-install your GFX card, and boot the machine up, and reinstall the driver. If the newest driver for Windows 7 doesn't work -try older versions! This can/is a lot of times a "temporary fix" until another driver is released.

Hope this helps -if you have questions feel free to ask.