although ive never used this phone personally, it seems like either you have knocked a wire which connects the speaker to the power/output socket. best thing to do is disassemble and look for any loose wires and find where they might go, i doubt it will have snapped off as u wud have noticed if u did that. if that isnt the problem then all i can think is that when handling it u had residual static energy in your hands from socks rubbin on a carpet etc, and u fried the section of the circuit which deals with sound for that speaker. like i said though i have never done this to this phone, but those are my advice pieces coming from a general all round electrician