Dryer will not heat up please help

My Maytag ldg710 stopped heating up the other day. We turned the dryer on and a couple hours later, we realized it was still running and not warm. When I open the access door at teh bottom of the unit, there is no flame at all. I also do not see a glow from tthe ignitor. Where should I start or what do you think is the most common part to replace?