Go to the play store and install the "SoundAbout" app. I believe I had to restart my phone after I installed and opened the app before the sound started working again. This may or may not work in your case since you mentioned your phone was dropped in water but it's worth a try! The sound on my HTC Desire 626 just stopped working one day. It's very possible it happened from me dropping it bc I'm constantly dropping my phones, so give it a try. It might not be due to water damage after all!