In other words mciahel is certainly on the right track,,,,
But Generally speaking, on laptops those "touch sensitive" audio controls "aren't"...
("touch sensitive" that is...) They APPEAR to be and they are called "touch sensitive",
but how it's REALLY accomplished is via an infared LED and a photo cell which read the
reflection off your fingertip
In either case it is less likely that they have stopped working because of a "failure" of anything
other than the drivers that tell the notebook to respond to them.
Unless you've had the laptop apart recently?
I know on my very similar Dell notebook the cable to those controls is very easily pinched in the retaining clips that hold the switch panel/hinge cover to the notebook.
Gateway drivers are often available, but depending on how old it is you may have to search a bit on their site.
The Gateway name is now owned by Acer.
Just avoid sites like :"Driver wiz" and similar sites, try to get the drivers from Gateway/Acer