I have changed the heating element, the thermal fuse, and the therma stat but it still does not heat, what else could cause it to not heat?

With Dryer in Running, I would measure across each sensor, if they are intact you should read zero volts, if you read voltage , it is open, and needs to be replaced.
If the Element has voltage and is not heating, it is open. An Amprope is handy but not necessary.

You need to make sure you are getting 240 volts to the dryer. Check your breaker. Turn it off then on. If you have a volt meter you can check for power where the cord connects to the dryer.