My phone's volume isn't working. I press the volume buttons but the screen only says "ringer" and doesn't show me the level. When I go into the volume settings I turn it all the way up and I still don't hear anything except the ringtones.

Close all open apps by double-tapping the home button, then swiping up and off the screen with the app window (not the smaller icon).

Reset your device: hold down the home button along with the sleep/wake button until the screen goes black and you see the Apple, then let go. (No data loss)

Can you hear your sounds with headphones?

SSwipe up the control center from home screen, do you have a Bluetooth device connected?

Do this: Settings > General > Reset > Reset all settings

She reset all settings exactly as I described?

Next step is to back up and restore your software via iTunes.

This is basic stuff that every iPhone owner should know how to do. Read this article:

iOS: Back up and restore your iOS device with iCloud or iTunes

This has happened before. Either your phone thinks it is docked because of some issue with the 30-pin port, or it is defective. In my wife's case it was the phone itself, which was still under warranty and the local Apple store simply exchanged it for a new one.