Have you tried pulling the knob outwards? Maybe it's sticking in the "push on to light the pilot" position because of a bit of crud on the shaft or something.
That control knob is the thermostatic valve for the oven, by the way. If you can't get it to work it should be fairly straightforward and not overly expensive to replace it (or have it replaced), assuming parts are available. Some older thermostatic oven controls do not have replacements available anymore because they used mercury in the thermostat sensor.
