is there any way so that i can play mkv video files from windows 8 video apps??

Solution
Windows 8 video apps? You mean the metro app? No. Unfortunately you can't.

You can use VLC Media Player, which is a desktop app. http://www.videolan.org/vlc/index.html

It plays the majority of file types right out of the box, but you'll need codecs to play media like .mkv or .avi files. Download and install the combined community codec pack to play these, and all other media files with VLC. http://www.cccp-project.net/
Windows 8 video apps? You mean the metro app? No. Unfortunately you can't.

You can use VLC Media Player, which is a desktop app. http://www.videolan.org/vlc/index.html

It plays the majority of file types right out of the box, but you'll need codecs to play media like .mkv or .avi files. Download and install the combined community codec pack to play these, and all other media files with VLC. http://www.cccp-project.net/
 
Solution
Honestly, after ages of fiddling with VLC, custom-compiling mplayer with cigwin, XBMC, using mplayer frontends like SMplayer, and using the CCCP, I find that just plain vanilla MPC-HC with the off-the-shelf settings it what I recommend to people who want something to "just work." It's lightweight and has better or equivalent hardware decode and format support than VLC with less fiddling. Can't get it for mac/linux though, then I suggest VLC.

http://mpc-hc.org/
 


You do not need any additional codecs to play most MKV files with VLC.