Sound doesn’t work on my appletv

… but when I entered to the app it was through a third party-our local tv company

For the Apple TV app on third party devices, see if you can delete and re-install this app. Then try again.

Else please contact the Support staff: Contact Apple for support and service - Apple Support

when I tried to go in through the apple tv box I didn’t succeed to even play anything

Sorry to hear that. Let us know if you are willing to invest time and effort into fixing that, perhaps suggestions from this community can help.

Do you have the Apple TV box? If so, which model? [1] [2]

Or is this about the Apple TV app on a different Apple device? If so, which device and model?

Or is this about the Apple TV app on a third party device? If so, which device and model?

Or is this about browser access to Apple TV+? If so, which device and OS?

What is your audio setup? Do you use a TV’s built-in speakers, or something else?

I tried to do a bunch of things

I now still have no idea what you already tried, so some suggestions may overlap.