It's possible to have the codecs installed to decode the video stream within a file, and not have the codec to support the audio stream.
Install video lan player from website videolan dot org (it's a freeware app that does not install any crapware ) - it has very good codecs for hundreds of file formats, and is generally pretty up to date. It's a good alternate to whatever your main media player is. Divx also makes their own free player, and Media Player Classic is a 3rd good free option. Just make sure you get those from trusted sources if you don't use vlc, and for all of them, if you already have a main media player that you like, then de-select the file associations updates during the install of the program - otherwise, any time you try to open the media files, the new program will do it. (I happen to like vlc so use it as my default - but you might not want to do that). Once installed, you can always select the alternate app to open a file by right-clicking the file and chooseing 'open with...' - which is a good way to try vlc for a single file.