Do you have all of the outputs going to deparate places? If so, it's unlikely that all wiring came loose at the same time. Check to see if you have your mute on. If none of those are the case, try at your own risk, turning the volume ALL the way up. If something is connected you will hear it in the speakers. If it's all at real low volumes you might have wires shorting out. Turn it up only for a second, and you really shouldn't do it at all. Also, do you have an amp connected? Are all outputs from the HU routed to the amp? In that case it is more than likely your amp. Make sure the amp is getting power at the amp, and that all speaker connections are connected. You can try the ghetto tried but definately true method of determining speaker connections: Take a 9 volt battery and jump it to the various speaker locations. If you hear a pop the speaker is connected. However you should disconnect the speakers from the amp or HU as I doubt there's a protective diode inside either unit protecting against involtage.