If your audio device gets disconnected/switched, Minecraft won't have sounds.
Steps to replicate:
1. Launch Minecraft
2. Disconnect audio device (by detaching USB connector)
3. Reconnect audio device
2. Switch to a different audio device (eg. Headphones -> Speakers)
Game sounds won't play and you have to relaunch Minecraft.
Have a setting in Minecraft to set the audio output to the selected audio device