Welcome to Android Central! Please clarify -- by "earpiece", do you mean the built-in earpiece speaker, or are you talking about a separate wired or Bluetooth headset?
If you're talking about the built-in earpiece speaker, then be aware that media sounds don't come from that speaker. I checked the reviews for that phone -- it doesn't have stereo sound, so media sound only comes from the speaker at the bottom of the phone.
Make sure the earpiece speaker opening isn't clogged by lint.