Ipx-550.mkv.mp4 -

If you need to change the actual format (not just the name) for better compatibility, use a tool like Handbrake :

This often happens if someone manually renamed the file or if a conversion process failed to replace the old extension. Usually, the last extension ( .mp4 ) is what your operating system will try to use. 2. How to Play the File If your media player shows an error, try these steps: IPX-550.mkv.mp4

If the file won't open, it may be corrupted or a "fake" file (common with oddly named downloads). Right-click the file, select Properties , and check if the file size matches what you expect for a video. 3. Fixing the Extension If you need to change the actual format