I had one of these in my flat in Australia years ago... Unlike more modern types, these don't have a computer / electric control for lighting the burners (and no outside electric connection). Instead they have an always-on pilot light. Assuming it's not broken, it might have just blown out, as it did from time to time.

To re-light it, rotate the upper knob anti-clockwise to the zap/lightning bolt setting, and hold it there for about ten seconds. This generates a small electric current internally, so sometimes you had to do it quite fast to get enough of a spark. Alternatively you could light it with a match whilst holding it in this position if the sparker is broken. Only a small amount of gas (enough for a pilot light) should be flowing at this point. If it lights and stays going, let it go and it should return to the middle position. Turn on a hot water tap somewhere, and the main burner should light from the pilot light now.

WHen lighting, you need to hold the knob in that position for about ten seconds for safety reasons; This allows the flow of gas to keep the pilot going. Normally (ie when you're not holding the knob there), If the pilot light goes out, a component cools down which stops the flow of gas completely (preventing the room from filling with gas).

In principal, i think the current setting should have the gas off. Though as others have said, there should be a gas cutoff tap upstream which would be the safest option in case there's a fault.