After a recent long road trip, I found that my front speakers don't work any more. There is almost no sound coming out of them. Did I accidentally mute them or what? Is there such a **** to adjust that in my car. since I don't have the owner's manual, will any warm-hearted person give me a hint or something like that? I am afraid that the 5 hour non-stop music shot my front speakers or AMP? Thanks in advance.