Car Radio Problem - Nissa Sentra - Sound only coming through right side speakers - Can anyone help?

If the left side door speakers are dead but the pillar mounted tweeter is still working, then you need to test the speakers. The tweeter is wired in parallel to the front speaker, so if it works, and there is not a broken wire going to the front door speaker, it should work.

A more common problem would be that none of the left side speakers would work. This would indicate a problem in the radio, whether it is the stock system, or the premium system with the Rockford Fosgate amp in the trunk. It would be unlikely that two speakers would fail at the same time.

Highly unlikely it is the radio. The tweeter mounted on the pillar would not operate if this is the case.

I'd check the wiring to the door ... possibly you may have opened the door too wide and something somehow got disconnected and the like. Since this happened rather sudden, I doubt you blew both left side speakers together at once.

Have you checked the 'Balance' option on your radio? You could have it balanced to the right side. Yes, it could be your radio. Often the channels are linked by side (front and rear left; front and rear right). It doesn't sound right to me though, with somthing coming out I suspect it's your balance.