Either the front speakers are shot, or not hooked up, or there is a problem with the head unit. If they were hooked up in reverse polarity they would still play, but would be out of phase (out of time with the rear speakers.) It is unlikely that the head unit is the issue but it is a possiblity.
Are the speakers the stock ones? If so they are likely the problem in my my open opinion.
Take one of the sound bar speakers out and connect the wires from one of the front speakers to it. If it works the front speaker is the problem, if not itbis either the head unit or the wiring. You can also look pull the radio out of the dash and check that the front speaker wires are connected.