My furnace is out and this has happened before... it just needed to be reset. I need help locating the reset button on Janitrol model GMP100-4, serial #9403029893... can anyone help?

Where is a reset button usually located on a furnace?

I know of no reset for a Janitrol gas furnace. If there is one it might be on the high limit control. Look for a circular control as big as a quarter with wires attached.. There might be a red reset button in the center. Your furnace might not have this device. Careful. Turn off power before you hunt for the part.