Audio Systems: Left side of my sound system is dead., nissan sentra, rockford fosgate

Question
I have a 2002 Nissan Sentra SE-R with the factory Rockford-Fosgate audio system (factory sub/amp, speakers, etc).  Recently the entire left side of system, plus the sub, all went dead.  Sound still comes out of the passenger side speakers.  The Fader/Balance controls are all normal.  What could be going on?  I have pretty limited understanding of how car audio works, so keep that in mind when you answer.:)  Thank you for your time!

Answer
if there is a short on one of the speakers, it turns off the amplifier on that side
so check the speaker is this vehicle been in a car accident ?

if not the amplifier go bad if water gets into the unit  
or it can be the radio that one side of the preamp output is bad

all the speakers don't go bad at the same time so that is not the case


good luck