I had a similar thing happen in Albuquerque a couple of months back.
I had drained and flushed the fresh water tank and put about 1/3 tank back in while I was all hitched up and ready to go and tried to wash my hands...
And no water...
I tapped on the water pump with a hammer and it started making a noise...but still no water!
A couple of expletives later and a run to the park's bathroom to wash my hands I decided to try and figure it out once I arrived in Flagstaff (was on my way to Yuma, AZ for the very first time).
Anyway, when I got to Black Bart's in Flagstaff I turned the water pump on and it made a hum, so I turned the kitchen faucet on...WATER!
And it has worked ever since!
I think maybe it was vapor locked with air and the bouncing around on US40 knocked it loose!
Ironically, once I got to Yuma I liked it so much I bought a park model in the RV park where I was staying in my 5'ver.
Matter of fact, I'm getting ready to put the 5'ver in the storage lot here in a few minutes and I just used the water pump awhile ago and it is still working fine!