Hi there and welcome
To confirm, you have windows 8.1 correct?
You do a reinstall of media player to reset it
To do this, press the windows key + X and click on Control Panel.
Click on uninstall a program.
Click on Turn windows features on or off
Uncheck on Media Features and click ok.
Let it complete and when it has, restart, go back and check it and click ok and it will then be installed again with default original settings.
I can also do these steps for you, and have made a request via Additional Services. This is optional, and if you choose to do this, I can, with your permission, remote into your computer while you watch and do all these steps (and deal with any problems that arise during them) for you. Or if you do not choose to take this service, we can continue here. This is no problem at all. Just let me know please.
Else let me know the results please.