My son's townhouse in Raleigh had two wall mounted switches for the gas fireplace. One ignited the logs and the other powered the noisy fan.
There was also a rocker switch (IIRC) wired into the system and located adjacent to the gas valve. This switch determined whether the fireplace could be ignited from the wall switch (something you would not want with toddlers) or if you had to crawl on the floor, lift the door hiding the gas valve, and ignite the logs there. Naturally there were no instructions, but being an engineer it immediately became a personal challenge for me to get it operating. I won!
Look for another switch located close to the gas valve.
As far as who could do this work if additional wiring is required? I would talk to a fireplace company and have it included in a proposal for a full safety and operation inspection. If the wall switch is there and not functional you should find out what else may not be working correctly.