I went to adjust the volume of the game in the audio options, since it was a bit too loud for my liking, but now everything has gone dead silent, and no amount of further audio adjusting or computer restart, or even an uninstall/reinstall can fix it. Can someone help me fix this?

(Weirdly enough, if I don't have any earbuds plugged in, the speakers play all audio and sounds just fine. But I want to listen to the game via the earbuds/headphones.)

Just got the same problem.

But this could be easily solved. It seems that when you're trying to fix game's volume it makes app completely mute. Just alt+tab on desktop while game is running, and check Windows sound settings.
Game's sound was disabled somehow. Returning it to full volume fixed this problem.

See picture attached for more details.