I got my PPC 6700 from sprintpcs in mid-July.  It's been a while since
it stopped to produce any sound, even when not in vibration mode.
Plus, playing music or video does not produce any sound. Tapping the
screen does not produce any sound, even if I have enabled sound for
screen tapping.

It's very weird, on rare, totally unpredictable occasions, the sound
may come up for a few seconds and then goes back to silence.

I googled a little, some people say that it is because the earplug
jack has messed up, and what they did was to repetitively plug in the
earphone and take it out until the sound comes back.  But I've had no
luck doing this.  Welling, I can hear the sound OK with the earplug,
but I want to hear the sound without an earplug.

Anybody's having the same problem and what's the solution?  Thx.