Finding the Windows key for Dell Computer

[mizzpenny]

I have a Dell computer that needs to be reformatted and it is currently booting into Windows

So I have 2 questions:
1) So the computer was upgraded from Win 7 to WIn 10 as part of Microsoft's Automated upgrade to win 10. If I need to format and reinstall, how do I install Win 10? which windows key do I use?
2) The usual Dell sticker that contain the Win 7 key is missing on my desktop is missing. If I needed to use the Win 7 key, how would I find this?

 

[Colif]

Since you upgraded to windows 10, all you need is a copy of win 10 installer - see here: Win 10 Media Creation tool

You don't need any key. When it gets to the screen in the installer that asks for a key, just click I don't have one that is on the right along side the next key and Win 10 will reactivate itself when you logon using your windows account after windows 10 is set up.

Microsoft have a record of your pc matched to win 10 on their servers.

How to do fresh install: http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html