Well, I don’t understand here right. Had you downloaded it compete ? If you didn’t, you must wait till there is ’download succesful’ in your torrent window. You couldn’t open it before.
Or, if you do downloaded it and WMP don’t want to play it, you probably haven’t got necessary codecs installed on your PC. You should download codecs and install them. The best way for you would be pack of codecs - All in 1 for example. Try this link: http://www.free-codecs.com/download/Codec_Pack_All_in_1.htm
It is exe file, after download (it’s 5,1 MB) and install it you should see almost all video and audio files. Usually no problem with it.
But now it's time to be gone - forever...