Windows 10: Reactivating Win 7 VL key for win 10 after hardware change

We Purchased Win7 VL keys back in 2010. In 2015-2016 we upgraded to Windows 10 & used the same key to activate. During last few years we required to format the PCs many times & every time PCs were getting activated automatically with digital license.Recently we required to change the hardware. But after hardware change our VL key is getting activated neither automatically nor manually. We want to know the way out.Thanks.-HCGNA

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is hardware OK (Win 7) for upgrade to windows 10

I think in one of the other PC with win 7 or win 8.1 I run media creators tools and in some step prompt/found graphics card not supported... for win 10. I didn't found alone reading specs of win 10, but
the tool says me... after changed graphics card the tool says all ok and continued ok... That I ask to reach this step in this current PC - win 7 - must be all ok for the upgrade? Or must continue to upgrade to show this?

and got to point

• UPGRADE this PC now
• Create media(DVD, USB stick, ISO)

is hardware OK (Win 7) for an upgrade to windows 10 for this PC???

 

is hardware OK (Win 7) for upgrade to windows 10

I think in one of the other PC with win 7 or win 8.1 I run media creators tools and in some step prompt/found graphics card not supported... for win 10. I didn't found alone reading specs of win 10, but the tool says me... after changed graphics card the tool said all OK and continued OK with upgrade... That I ask to reach this step in this current PC - win 7 - must be all OK for the upgrade? Or must continue to upgrade to show this?
and got to point

• UPGRADE this PC now
• Create media(DVD, USB stick, ISO)

is hardware OK (Win 7) for an upgrade to windows 10 for this PC???

 

Fresh Install of Win 10 without Serial Key?

Looking to reformat a laptops HDD, and then reinstall Win 10 fresh. The problem is it came pre-installed with Win 8 and I did the free upgrade to Win 10. How exactly would I re-format the HDD, reinstall Win 10 and ensure it reactivates properly? I don't see a Win 8 serial key anywhere in the contents of the box.