Does the DVD have a headphone jack? If it does, check that and see if it works.
If it works, try a headphone on the surround sound amplifier.
If that does not work, check wires from DVD, if it does work I would double check the wiring to the speakers (on the back of the surround sound and at the speakers). The wires can break right at the speakers or touch or you can 'crimp' them on the insulation (not that *I* have ever done that).
If that all looks OK, do you have another speaker and wire you can try to connect just long enough to verify operation?
If that does not work, could volume be turned down?
If still does not work, I would disconnect all speakers from surround and try just one known good one and wire.
If still does not work, see if where you bought it can test it.