Sorry, since we can't see your computer from here and have no idea what
changed - you can't get focused help. We won't be able to tell you what
you did because we weren't watching you, but we might be able to tell
you what to do to fix things if you give more information.
try upgrading your media player or uninstalling and reinstaling recent
hardware uprades. Make sure that you don't have hardware failure, ie
your sound card has no problem.