Hmm, nothing but guesses really. It really shouldn't do that.
For music maybe you've accidentally hit N or M which toggles mute. Are the sound effects still playing? What about if you check the menu, is the music on there?
You sure you are using the same browser as last time and it wasn't an incognito tab? And what browser is that by the way? Also, when was the last time you played? It's very weird that the music state seems to have saved but the overall progress wouldn't have.