It's not that easy esp. given:
I am just barely computer literate.
There is a way to do it by stopping certain services and editing the Registry. Not something that you probably should try. I've got decades of experience with PC's (former ASU Network Mgr.) and I don't even like Registry hacking unless I have to.
And I really
DON'T think that's your problem.
I'd check with the company again first as you already
have Windows Media Player 12 installed - it was part of the Windows 7 installation. AFAIK there hasn't been an upgrade to it yet. So they may have assumed you have an older version of Windows. (everybody blames Microsoft..)
Just the fact that they told you to uninstall it from the control panel makes that advice
suspect as anyone familiar with Windows should
know that's not possible to do so from there - as you've also discovered.
You probably received a response from some tech support "guru"
who is reading it off a prepared script.
I wouldn't start hacking my W7 install unless they provide detailed instructions on what to do.
If you really want to try it, contact your computer mfr's tech support and have them do it remotely via Windows Remote Assistance - they can do it over the Internet if you let them access your computer temporarily.