I would test each injector plug, see if any are getting power. If at least one lights up, it is most likely the connections to the injectors or the harnesses, if none are I would check the connections to the PCM, see if there is a dirty plug or any broken wires there.

There's two things that can disable all of the injectors in the PCM, traction control and the speed limiter, if that gives you any ideas...

And like I always say, check and clean every ground location you can find.