Welcome to the forum.
Should be able to move filter and move wrench up from bottom of filter.
Also check the valves from the fresh water tank and make sure the valves are in the direction of the pipe, you have a filter on pump also that could be plugged.
The city water valve needs to be closed for any water to flow from pump or the city water direction through city water valve.
Here is a link
to different water systems that you can input your coach and year which may show you your plumbing system if you change the search information.
Your water pump maybe in a bay next to your water heater up to your right, you have to look inside with a flashlight to turn the water valaves on your by-pass valves for your water heater and there should be a plate on wall above the opening with the positions to open the water flow.
Number 2 in this link will
show the water valves of water heater.
We also have a TSB LINK
that will give you info on your coach for brochure, owners guide and other needed info.
Below in my signature are links to other info for your Newmar.