Every electric oven has at least two heating elements inside. One element is located on the inside top of the oven while the other is on the inside bottom. Over time these elements will begin to weaken and will eventually burn out. Several factors can make the heating elements wear out faster.
If you drop a heavy pan on a heating element or if the element is quite old, it might actually break in half or have a deep nick in it. Let the heating element cool off completely, and then check it using a flashlight. The element will not work if there are deep nicks, scratches or breaks.
Blistering occurs on heating elements as they age and the metal has degraded. This can also occur when food drips directly onto the heating element while the oven is on. The metal on the heating element will actually bubble up and blister, causing a break in the electrical continuity. This is irreparable damage, and you'll need to replace the heating element to fix the oven.
Test the Elements
Just because the element isn't turning red or heating up doesn't necessarily mean that it is broken. Other electrical components, such as the igniter, may not work and may be preventing the element from turning on. To test the heating element, unscrew the screws that hold it in place and pull it from the terminals at the back of the oven. Use a multimeter by connecting one probe to either side of the terminal. This will test for continuity and electrical flow.
Install a New Element
Install a new element by attaching the ends of the heating element to the terminals. The element will simply press and lock easily into the terminals. Then secure the heating element back in the oven by tightening the screws in place. The heating element generally has two or four screws.