No sound on downloaded .mp4 videos

Pat D 4 months ago in FVD Downloader • updated 4 months ago 2

I have recently downloaded some videos (.mp4) from a membership training site to my personal computer. I believe they are hosted on Vimeo.  A few of the videos have sound but most of them don't. All of the videos work properly but some of them don't have sound. I have tried them in several different video players with the same result. I have installed the latest codec and verified that my hardware is working properly. Do you have any suggestions on how to get the audio to work with the videos? Thanks.