What program do i need to run a MKV file??

...If I only had a dime for how many times I've had to answer that one...


Get a codec pack like K-lite (http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm) or CCCP (http://cccp-project.net/); or you can get the matroska codec direct from their site (http://www.matroska.org/), though this way doesn't work, typically, as it requires either avc or h264 codecs on top of the matroska.

After you choose your install, you should be able to just double click on the file and watch it run. If you look on your task bar, you should see an omega-like icon in your traybar (lower right). If you right click on that, you'll get a few options like Audio track (the language), or subtitle track.