: Right-click your file, select Open With , and choose VLC Media Player .

The most reliable method is using . It is a free, open-source tool that "just works" with almost any video format. Download : Get the official version from VideoLAN . Install : Run the setup and use the default settings.

For a quick visual walk-through on how to get your MKV file playing on Windows, check out this guide:

: If VLC doesn't work for you, MPC-HC is another lightweight, safe option for Windows.

: Right-click the file > Properties > Change (next to "Opens with") > select VLC . Important Safety & Quality Tips