Electric Burner Not Heating: What’s Replaceable and What Isn’t

Three cooktop types, three different answers. On one of them the element is a plug-in part; on the other two the repair is behind the glass and it is not yours.
If You Smell Gas at the Stove: Stop and Do This

Leave the building. Do not touch a switch, a light or a phone on the way out. Call from outside. There is no repair on this page and there should not be one.