Windows 10: I updated windows and now my computer has no activation key

I left my computer for the weekend and when I got back my windows kept telling me my key was about to expire I looked up a fix and a forum post said typing slmgr /upk fixed it for them i ran it in the terminal my pc then said your key has been unlinked and then it crashed now I've reloaded my pc and I have no key at all what should i do?

:)

 

windows 8 activation key

You can use a Windows key as many time as you want provided it's only on one computer at a time. If the automated activation fails, just call the number it provides. Six minutes later, you're activated again. If it asks you how many computers it's on, just say "one" and you're golden.

 

Windows 8.1 pro + WMC key activation

This worked for me last time with a Win 8 key.

Install Windows 8.1 and enter KMS key during setup. Once in windows change product key to my Windows 8 key. Go to add features and enter my WMC add-on key. Drink a beer to a job well done.

 

Windows 8.1 pro + WMC key activation

So it will be fine installing 8.1 pro with a KMS key, then switch to my 8 pro key and it will activate ok?

Maybe a daft question but why can't you just install 8.1 pro with the 8 pro key, or is it different keys for 8 and 8.1? seems silly when 8.1 is a free update anyway.