So your saying no gas and no ignite? That's usually not the scenerio in most cases you should always have gas coming out no matter if the ignitor is working or not and is more of a mechanical problem as where the no ignite is an electrical problem in most cases. There's wiring that fits on top of the burner valve which may have an issue also if you don't have gas coming out i'm suspecting a bad burner valve for the no gas problem.
As far as the no spark issue which usually is separate there are things to check listed below.
1.Poke gas orfice down in unit with a safety pin to clean any carbon buildup in orfice
2.Clean any debris and take a wire brush to burner head and caps cleaning them of carbon and boil over and food buildup.................Most units have the ignitors all light at the same time or some have 2 spark modules. You could either have bad ignitors or food on the ignitors clean them with a piece of sandpaper gently and test again. If this doesn't solve your problem check to make sure your ignitor wires are connected good at the ignitor and spark module. Do not voltage test these with the switch trying to ignite it will blow your multimeter.
Last but not least if all these things fail you may also have a short in the ignitor wires but more then likely i'm suspecting a bad spark module since you have multiple burners not working should be located in the back of the unit or underneath the cooktop. Modules can be fairly cheap so if you see any burning on the exterior of the casing it should be replaced.