Im lost past a factory reset.....i had that same problem with my first og droid. It thought i had a set of headphones plugged in after it got a little wet. It got stolen before i had a chance to remedy the problem so i cant tell you what i did......either way good luck brother. Ill be interested in seeing what happens.
I m having same problem aswell i did factory reset it did nt work aswell though i/ve noticed if i tap gently on the speaker it does works for a while but i guess i\ll send for warranty claim