My IPhone 4S Volume/Ringer won't work?

Ok so my phones a year old or so and it was my dads first. He dropped it in a lake and the lights permanently on then a couple days ago I dropped my phone screen first into mud and the volume won't work… Any ideas of how to fix it?

Possible solutions:

1. Test out your sound if it works by playing music.
2. Test out your sound by going to Sounds in Settings and adjusting the volume bar and changing ringtones and SMS tones.
3. Tell someone to text you and call you and see if any sounds pop up.
4. Turn off your phone for 1 minute then turn it back on again and see if it works.
5. Restore your iPhone.

If none of these work, bring it to the Apple Store or seek Customer Service. Also if you have warranty on it, get it renewed while you still have it.