Open Question: Windows media player?

My windows media player used to play every movie or show i downloaded from Frostwire but one day my cat stepped on the keyboard and the small rectangle changed to a very tall rectangle and now says the codec isn't supported for all the videos I try to watch unless it's one of the videos I had already downloaded before this happened. When i say the box changed I mean the shape of the player while it's loading the movie. Any ideas?