My speaker is not working

we could provide some information based on 'my speaker is not working'

disconnected wire is usually ALWAYS the cause.
could be a wire on the back of the speaker.
could be a wire on the back of the speaker box.
could be a wire on the back of the amplifier.
could be an electrical trace inside the amplifier.
could be an electrical trace inside the voice coil.

maybe a shattered magnet on the speaker?
 
Change leads of the speaker wires meaning right to left and visa versa. See if it is the speaker or something else.
 
There is a web site called Fix It try them.I would take it to an reputable repair shop in your area and have them look at it.