Hi AmandaScott,
· Have you made any changes on the computer prior to the issue?
Follow these methods.
Method 1: Run the media player troubleshooter and check if it helps.
Open the Windows Media Player Settings troubleshooter
http://windows.microsoft.com/en-US/windows7/Open-the-Windows-Media-Player-Settings-troubleshooter
Method 2: Perform a Clean Boot to see if there is any software conflict as clean boot helps to eliminate software conflicts.
Note: After clean boot troubleshooting steps, follow Step 7 in the link to return the computer to Normal startup mode.