: Right-click the file and run a scan with your antivirus (like Windows Defender or Malwarebytes).
: Download VLC Media Player or MPC-HC . These are the "Swiss Army Knives" of video; they can open almost anything without extra configuration. tfpdl-tblklst100372x.mkv
Once the file is playing, you might find the volume is low or you need subtitles. : Right-click the file and run a scan