Reinstalling Windows 10 from a Prior Upgrade

I upgraded my Windows 8.1 desktop to Windows 10 in August using the ISO Media file. Due to a computer crash I had to reinstall Windows 8 from the original Windows 8 disk. I ran the update to install all Windows 8 updates so that the computer would be ready for Windows 10. I then went to the Microsoft site to run the ISO Media file. However, during the setup process it asks for a Windows 10 product key which naturally I do not have. I tried using my Windows 8 product key but it would not accept it. Is there a way now to upgrade to Windows 10? If not, then I will just stick with Windows 8.1 until Microsoft forces me to upgrade to Window 10 via the Automatic upgrade process.

Yes, just click Skip when asked for a key. Make sure you select the correct version Home or Pro that you had before, or it will not activate.

Use the "Upgrade this PC now" option of the Media Creation Tool. If you are trying to upgrade from Windows 8.1 to Windows 10 again and it is asking you for a product key, then you have the wrong version downloaded.

Since you've upgraded once already on that computer - there is no need to start over with Windows 8.1. If you download the same version of Windows 10 you had before and are entitled to and create an installation USB or DVD you can just clean install Windows 10. That is when you would "skip" or "do this later" when asked for a product key.

I think your best option is a clean install with the correct version and skip the product key page. Your hardware should be logged with Microsoft so you don't have any activation issues. Upgrade installs, where you install on top of a previous install, have issues.

I have spent two entire days on this and it is too complicated for me to understand so I have decided to just stick with Windows 8.1.

There is no complication in this. Boot with Windows 10 DVD-ROM or USB install media you have prepared. Start setup and at the disks delete any partitions (assuming you already have a backup of your data). Proceed with the installation. When asked for a key click skip and select Windows 10 Home, if you had 8.1 core or Windows 10 Pro if you had 8.1 Pro. Leave it finish (can restart automatically many times until complete). Complete the initial user account etc stage and when at the desktop install any drivers. Then run Windows Update to install any remaining drivers you didn't have and you should be OK.

After working on it for another of hours I was able to do a clean install of Windows 10. Thanks for the help.