I spilled soda on my Chromebook, why won't the sound work?

I am also confused as to whether you are concerned about your earbuds (an accessory), or the actual Chromebook. Either way, it sounds like the liquid penetrated far enough into whatever device it was spilled on and damaged it to the point of it not working (if that wasn’t obvious already).

With that said, I would say you either need to replace the speakers or earbuds. If it is the Chromebook’s internal speakers, you may get lucky and be able to clean off the tabs where the speakers connect (as well as the speakers themselves if they are sticky or clearly affected by the liquid) with some isopropyl alcohol, preferably as a swab. BD sells some, for example. Just a note - this is a mere suggestion, I have not done this before. Just be sure that if you do, you do not soak the items, but gently rub off the residue. If there is still any liquid, soak it up with a cotton ball or microfiber towel.