It was in English!!!!!
So can I assume you have installed the FULL set? personally I would uninstall it. try and play the file. Again, I am assuming Windows Media player here, correct me if incorrect. WMP should prompt you to download the codec from microsoft. let it do it( not a dodgy copy I hope although I don't think they check for codecs). Tell us the result.
I'm not a fan of 3rd party codec packs, its too easy to get something a bit screwy.