Do you get a picture on the TV? If so and you are really lucky, the TV might have internal speakers that are turned off, with the sound output going to the sound system instead. If so you might simply have to turn the sound of your TV on as a temporary fix. Check the TV manual. If you don't have one, find the model number and search online.
If you get a picture and the TV does not have speakers (like mine), you might be able to connect the TV's red/white RCA audio output to a cheap boom box from Walmart to get you home. (Mine doesn't have one either.)
I can't help you with suggestions of who to take it to in order to have the work done. I have always chosen to do my own work in the entertainment area. And the entertainment system was an area that WRV was always changing, so what works for one coach might not work for another, even within the same year.
My coach came with a Panasonic "home theater in a box" system for a sound system. When it died, I found very few sound systems that would fit into the cabinet. I wound up buying a newer version of the same Panasonic sound system.
For what it is worth, I just bought a Panasonic SC-BTT190 Blu-ray "home theater in a box" system, and planning to install it myself this weekend. It has a small footprint and will fit in my cabinet. And it has the same types of connections as I already have.
I looked around before I bought it, and could not find any AV receiver systems that would fit in my cabinet, at any price. The Blu-ray system I bought is NOT an AV receiver, but it will suffice for how my system is set up. But your cabinet is likely different than mine and the whole system is undoubtedly set up different, so they may find something that will fit as a direct replacement.
'04 Alpine Coach 36' MDDS