I presume you are referring to the temperature control for the oven. Can you tell us more? Does it not work at all with no gas to the burner, or is just out of calibration?

If it needs calibration, pull the knob off. Does it have a hollow shaft? If so, there is probably a calibation screw inside and at the bottom of this shaft. It is accessed by a small, flat blade screwdriver. Turning this screw adjusts the set point of the control. It takes some fiddling and time and an oven thermometer to get it adjusted. Temperature lag due to thermal mass increases the difficulty.

If the control does no control and allows the flame to burn all the time, it is dangerous becasue it can overheat the oven. It should be replaced or the gas supply to that burner disabled.