Problems reinstalling original OS

I recently installed W10 on my gfs laptop (a Pavilion DV6). I found out she had a 32bit version of W8 installed on her 64bit pc (which was my mistake). Therefore I couldn't automatically update her laptop to Windows 10. I needed to do a clean install of W10 instead. But, since it was a clean install, her laptop couldn't be activated...

I looked around and read that I should have rolled W8 back first, to the original W7, then update to W10 to be able to activate the pc.

Now one of the video drivers isn't working for some reason and gave me a code 43. I started troubleshooting to fix it, which worked. After restarting 2 or 3 times though, the problem was back. So, now I want to rollback W10 to W7 (to ultimately go back to W10), but I read that W10 does not use a recovery partition, therefore it's not listed as an option in the recovery settings of W10...
So, how can I get back to the original W7? Is it still possible? Or any other fix possible to make her videodriver work properly? We already have the original drivers downloaded from the HP site.
 
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