How To Find Windows Activation Product Key

If your computer is still working and you can access the Hard drive install Belarc: https://lozaelec.blogspot.com/2011/06/lost-your-windows-software-key.html

If your drive is currupt or dead, install a new hard drive then reinstall the correct version of windows either home or pro if not it will not activate, 

Install windows 10 without internet connected and when it asks to activate windows 10 select do it later.

As long as your mother board has not been replaced your product key should be embedded in your Bios

Once windows 10 is installed 

1) Go to Search type cmd, then right click on Command Prompt, then select Run as administrator

Next type or copy and paste:  wmic path SoftwareLicensingService get OA3xOriginalProductKey

Must be done from c:/windows\system32 folder

Key will displayed below

In search type activate, then change product key and add your lost windows key

Be aware this only works for brand new installations of windows that is not activated, it will not work with computers that already activated with a digital licence only key licence, it will display no key.

When I first created a windows installation USB it was a Windows Pro version and after I retrieved the product key from Bios using the above steps it wouldnt activate windows 10, i then realized I should have created a Windows Home USB installion, it then activated.

Windows Media Creation Tool. :https://www.microsoft.com/en-au/software-download/windows10