Since the dryer is not heating at all, I recommend checking the thermal fuse first. To check this component, follow these steps:
If the thermal fuse is okay, then you could have weak or failed gas valve coils that are preventing the dryer from heating properly. The third image below explains the operation of the gas valve assembly in your dryer. Understanding this process could help you determine the heating failure that you are experiencing in this dryer. I would need to know more details to help you further with this problem. I recommend checking the issues described above and resubmitting your question with more information if you need more technical help in resolving this heating problem in your dryer.
To view a parts list diagram of your dryer and order parts, you can visit, www.searspartsdirect.com.