A MKV or Matroska file is a format that can support a huge number of video, audio, picture or subtitle tracks inside a single file. The menu options on MKV files are quite similar to a regular DVD menu. An encoder is present within this file along with compressed video and audio streams, therefore you will need a codec to read it. Theses codecs can easily be downloaded from the Internet. Its main purpose is to create a format with multimedia storage along with being completely open source. In many ways, MKV is similar to other containers such as MP4, AVI, ASF etc, but it is overtaking other formats such as MP4 and MP3, because of its various advantages. The main advantage and feature of an MKV file is its ability to hold unlimited open-source video, audio and subtitling tracks within the single file format.

MKV files usually have three extensions:

.mkv – Include subtitles and audio
.mka – Include audio-only files
.mks – Include subtitles only

How to play an MKV file?

The first step would be to download an appropriate codec. After downloading and saving, you need to install it on your PC. After installing it, right click on the file you want to open and open with your preferred application. If any error is encountered while opening the file, it is likely that you have not downloaded the correct codec. You can repeat the process again. 

You Can Download ac3filter and VLC Player to Play mkv files with out any problem 

1. Unarchive the package and use the files from Release folder if you're running Windows 9x/Me or Release Unicode if you're running Windows 2000/XP. 2. Copy DLL or AX files in system32 folder [ C:WINDOWSsystem32 ] 3. Click on Start > Run... • To install the files, type: regsvr32 filename.dll or regsvr32 filename.ax • To uninstall the files, use: regsvr32 -u filename.dll or regsvr32 -u filename.ax 4. In the end, you should receive a message saying that your file was succesfully installed/uninstalled. An easy way to register/unregister [install/uninstall] the files is to use one of these small tools: • RadLight Filter Manager - can be used to list all registered codecs and to register or unregister codecs. • DirectShow Filter Manager: helps to list, sort, find, add or remove DirectShow filters. • RegShell - a handy utility that will help you avoid the inconvenience of running regsvr32 from the start menu all the time. • DllRegSvr - allows to register/unregister DLL and OCX codec files using RegSvr32 tool. • Emsa DLL Register Tool - register dll/ocx filters, codecs... and get extended file informations