Hello.
Suddenly i can not hear people talking in voice chat (but they can hear me),
and nothing except Overwatch and Discord gives sound; for example if i alt-tab and play youtube or music nothing works, not even windows sounds.
This started happening after i changed the in-game spoken language, even after changing it back to default english, it doesnt work.
This sounds like an issue with exclusive mode on the playback device. You can fix that by going through the steps here (but for the playback device instead of recording device in the advanced section).