Why is my 2012 Nissan Altima radio not working?

There are a number of different reasons why the 2012 Nissan Altima's radio will fail to work, and it all boils down to precisely how it's failing. Is it just the radio that's failed, or is it the entire head unit (stereo) If only AM/FM radio is not working (but all other inputs are), then Your most likely culprit is Your antenna. However, it's a common failure in the '12 Altima that all stereo inputs will fail to work, and this can be traced back to either Your head unit itself, or a part of the greater sound system (speakers, wiring, etc). You'll need to start Your diagnosis by using something like a digital multimeter to test each component, and eventually You'll find Your issue.