Windows 10: how to restore a product key that has been deleted

I lost my product key because I typed slmgr rearm in cmd.

:)

 

Vista Product Key Question. (Legal)

I don't think so - I tried to sell a stack of OEM discs with no keys and MS threw a fit, so eBay deleted my listing. Try craigslist instead.

 

How to delete inactive System Image Restore Points in System Restore

Windows 10 64-bit.
When I click "show more restore points" in System Restore I see a bunch of old "system image restore points" that were deleted in past and do not correspond to any currently active restore points. Clicking any of these old restore points, I simply get an error message saying they could not be found, and to select another restore point instead.I would like to delete these restore points listings but have been unable to do so.
So far, I have tried steps mentioned below without any luck :

Disk Cleanup through (C Properties
Disable System Protection (OFF and ON) in System Protection for OS (C
Disk Space Usage to minimum (slider button all the way to the left then 'Delete all restore points for this drive'),
Delete all shown Restore points in CCleaner (the problem ones do not show here),
Reset Windows Backup to Default in Windows 10 with 'Reset_Windows_Backup.bat' utility.

Any suggestions highly welcome.

 

Product key

Hi Megan,

A product key is used when activating a software.
To help us determine the appropriate troubleshooting steps that can resolve your concern, we'd like to ask the following questions:

• What product are you trying to activate?
• Are you looking for the product key to activate your Office application?
• Which version of Office are you trying to activate? To check this, you can perform the steps posted on this
  link.
• Are you looking for the product key to activate your Windows?

We look forward to your response.