Before uninstalling it, have you tried going to the update center to see if there are updates for it that you may be missing? Usually if there are updates for Media Player at the update center, it will 'fix' or replace files missing or corrupt.
If that doesn't help, let us know...you might try booting up into safemode to see if you can use the Add\Remove Programs/Windows Components area to uninstall it....then reinstall after a clean boot and go to the update center to get the latest updates for it.
I am having trouble playing anything with windows media player. I want to know how to remove it from my system, it will not let me right now. It says access denied and the source file may be in use. Please help!!