If you do not hear any clicking when you push the ignitor button, it may be time to replace the battery.
To access the battery, unscrew the ignitor push button and collar. Remove the old battery. If you see any corrosion in the battery compartment it can be removed by wrapping a small piece of sand paper around the eraser end of a pencil and using that to scrape off the corrosion.
Install a new AAA battery into the battery compartment, positive (+) side down. Replace the push button and collar.
Below is a video showing how to replace the battery in the electronic ignitor.