Did you create a system recovery media set yet, or did your system come with DVDs to be able to set it back to factory default?
Most system recovery media gives 2 choices, #1 is to wipe drive clean and install all clean and all personal data is wiped out, and #2 perform a system recovery which does not delete all your data.
Since you tried to repair media player without success, I would use the system recovery media set on it and set it back to factory settings, then perform all system updates etc. Becore doing this, I'd backup all important data to an external hard drive or thumb drive to avoid data loss.