Assuming your pump is still working, have you filled the water tank, and is the monitor reading 100%? Open a faucet or two when you turn the pump on. That might help the pump get its prime in order. Is the water heater full of water? When the trailer was last winterized, maybe some some hose connections at the pump were not reassembled correctly?
Remove the large drawer under the oven, and look into the pump area. Any water drips or sucking air sounds? To figure out how to take the drawer off its slides, look at the drawers between the fridge and the oven. If you look at the underside of the top drawer, when it is pulled out, you can see how to push on the orange release tabs on each side near the drawer front.
We have the same year and model, so hopefully the steps above will make sense. If you get some water out of one faucet at least, go around and bleed the air out of all hot and cold lines, including the exterior shower.
You might also want to read the owner's manual on this.
Good luck,
Peter
PS -- There is a thread specifically for our model, with many helpful fellow 20' owners available to help:
http://www.airforums.com/forums/f542...rs-127845.html
PS2 -- You should always use an inline filter when filling the water tank [and when using city water]. If you filled the tank with just a hose [no filter], you might have grit in the pump preventing it from getting its prime.