dryer wont turn off or heat up

Hi i recently started having issues with my whirlpool dryer. It is a gas dryer. It wont shut off or heat up. reading through a number of posts it seems that most people have electric dryers and so i am not really sure what i need to be looking at or for. as far as i can tell the timer is working fine, when i turn it on it counts down, but, i am not sure if this does not matter in my case. any help would be much appreciated. Thanks.