how to uninstall windows 8.1?

My computer has to be brought back to Win 8 to correct a problem, since I upgraded to Win 8 from Win 7 via MS offer, and due to the Win 8.1 upgrade I no longer have my Win 8 Key, only 8.1.  So I need to revert back to Win 8 to recover my key, as MS rep says they have no way to give it to me.

So simply, How Do I Get Back to Win 8?

Ever since 8.1 was downloaded, I have not been able to properly use my work email.  It has also deleted printer drivers which were a handful to do in the first place. I really, really, really need to uninstall this.  Please tell me how I am able to go about this.  Thank you.

Since I updated to 8.1 I seem to have a new issue everyday and I can't seem to resolve any of them.  Windows Media Player will not work and now a lot of the start screen apps will no longer work. 

In addition to the above issues, occasionally parts of my screen go black when I am scrolling down the page.  If I click on the page, the missing parts will come back a little at a time.

I need to resolve the media player issue as I need it for my job.  I have tried the recovery option explained in this thread, but that did not work either.

Windows 8 was great and I didn't have any problems.  I really would like to get it back.

Thank you to anyone who has an answer.

Since I installed Windows 8.1 I have several issues and problems.  I want to UNINSTALL 8.1.  How do I do it.

I Had sky.com as my default homepage before I upgraded to windows 8.1 since then Ask.com is now my homepage and I cannot remove it as it is not in my programmes