There may be no sound if it has been turned off by the user. To turn on the sound, find a speaker icon in your system tray (Windows notification panel). Proceed to “Volume control” and increase the volume.
Another possible reason for the lack of sound in TeamViewer is the muting of the audio track in the editing software, player, or browser window. Carefully check the settings of the software used, and, if necessary, make changes to them.
Also, the sound may disappear if someone made adjustments to the standard parameters of TeamViewer. Open the Menu (hamburger button), then “Extras” and “Options”.
In the “Audio conferencing” section, uncheck the “Mute” box and increase the volume if necessary.