It is nearly impossible that a single problem could cause BOTH the 12 volt
and city water systems to fail.
It IS possible that a load of debris of some sort went through the system and has clogged up all faucets and even the toilet.
There is a filter, or should be, just ahead of the demand pump. Usually they are user servicable by removing the clear housing and washing out the screen. Make sure you get the housing seated properly or the pump will suck air into the system and it will drive you nuts trying to figure out what is wrong. Don't ask how I know this.
There is also a kinda sorta filter in the inlet of the city water inlet. There is also a bell shaped pressure regulator that conceivably could fail and shut off the water.
I think I would start with the city water supply, and open connectors, one at a time starting with the inlet to find where you no longer have any water pressure. Once you have that licked it should be easier to go to the demand side and see what is happening.