hello my friend
what you need is some codec to play your files.
i believe there are 2 fantastic paths you can go down,
you can download VLC media player from here http://www.videolan.org/vlc/
which will play every film you ever want it to and has fantastic features such as changing aspect ratio resyncing the audio, but as a player its not as pretty as WMP,
so if you wish to stick with your original video player then you will need to download a codec pack of which i belive k-lite codec pack to be the best, this is downloadable from here http://www.free-codecs.com/download/...codec_pack.htm
good luck mate