Start with the audio inventory
A file can contain several independent audio streams. The first or default stream may differ from the track a desktop player selected. Write down the codec, language and channel count of every stream, then try the player’s audio-track selector. An alternate track is the quickest useful test because it changes no files.
Use the report to distinguish “no audio stream” from “audio stream present but silent.” A conversion cannot recover sound that was never recorded. If other recordings from the same source are silent, inspect the source export as well.
Separate decoding from sound output
Test the TV speakers, then the soundbar or receiver. Record whether the problem appears on both. If only the external output fails, keep the file unchanged while reviewing that connection, input selection and audio output setting. A working picture does not prove that every audio route supports the chosen stream.
- Test the same short passage with an alternate audio track.
- Record the exact app and output mode.
- Keep a known-working reference file for comparison.
Make the smallest test copy
If the selected device documentation excludes the audio codec, preserve the video stream and test a separate audio conversion where your editor supports it. Choose settings that the destination explicitly supports. Listen for channel balance and lip-sync near the beginning and end before processing the full recording. The original remains your recovery copy.