Reinstalling win 10 lost my product key
If you’d Upgraded to Windows 10 from Windows 7 then when it first activated it recorded your hardware mark in MS Activation servers as a keyless Digital License so you can
Clean Install Windows 10 the same edition (home or Pro) as often as you want, miss out the Product Key, and it will activate after connecting to the web.
Activation in Windows 10
If it doesn’t activate soon then you either installed the erroneous edition or Raise was never activated before on that PC. You can open the Contact Assist app to ask for help with this.
Windows 7 that comes preinstalled from factory should have a COA label on the bottom of laptop or under battery with the Product Key used to
Clean Reinstall Windows 7. Inserting the old OS product Key into a
Clean Install Windows 10 is being phased out little by little as an activation method so still might go to work if nothing else does. Otherwise if you explain the problem to the agent via the Contact Assist app, they should help you get it reactivated.