Windows Activation  

EDIT
Refer to this link. There was a bug at Microsoft that caused many product keys to become invlaid for a brief moment of time:
MSFT acknowledges some Win10 Pro licenses being mistakenly deactivated - Windows 10 Forums


Hi, so just suddenly yesterday, my Windows said that it is no longer activated. I bought the Product Key from an online vendor in September 2016. They sent me a picture of the Product Key (I attached it below and removed some characters from it in the picture). I got this error in the activation (attached picture).

I tried pressing Troubleshoot, that didn't do anything.

I tried re-typing the product key, that didn't work.

I tried an online method to try an invalid product key, then try my product key again. That didn't work.

Any help would be appreciated.

See:

You should be able to now re-activate your Pro by using the command slmgr /ato in an elevated command prompt.

MSFT acknowledges some Win10 Pro licenses being mistakenly deactivated - Windows 10 Forums

Oh wow, okay thanks for that link Shawn! I thought someone hacked my computer and stole my Product Key and tried activating it on their computers or something. That brings me relief. Okay I'm not worried about it anymore, it's just a bug that Microsoft is experiencing. Hopefully they get it all fixed up. I saw that article in your link that they should have it fixed within a couple of days.

I also tried that command with my product key afterwards. It didn't work. No worries though.

I'll just wait a few days until it gets fixed by itself hopefully, by some Windows Update or such.

Worked for me, too. As usual, the forums and its stalwarts come through with flying colors. Thanks @Brink and @Bree. You rock!
--Ed--

I tried messing with that slmgr many times earlier today. It never works on my computer. I keep getting this message after trying that:

Okay I got it to work when running PowerShell as an Administrator, other than Command Prompt as an administrator. Thanks for the photo that Ed posted, it gave me the idea of trying those commands in PowerShell. I removed my key earlier somehow, let me fiddle around a bit with all this and hopefully get the Product Key to work again.

EDIT: Okay, I reactivated Windows. Thanks everyone for your help and hopefully other people didn't go through tedious online steps to re-activate their Windows.