It's likely your heating element has overheated and the ni-chrome heater wire has been severed. There are other potential root causes, but this is most likely the root cause. There are two temperature sensors in the heating element sub-assembly, one or both or which may have failed.
The most likely cause of heating element overheating is a clogged vent. To avoid future overheating, check the vent regularly and remove any lint build-up.
The heating element, the heating element sub-assembly, and the entire galvanized metal heating sub-assembly (which includes the two temperature sensors) are available for purchase. Here are examples of all three:
Before purchasing any component, verify model and part numbers match your dryer.
Before starting your repair, make sure the dryer is disconnected from its electrical source either by unplugging it or turning off its breaker. The dryer is heavy, so be careful lifting. Parts inside the dryer may be sharp to the touch, so be careful reaching inside. Use of gloves is recommended.
The heating sub-assembly is accessible from the front, behind the door sub-assembly, but may need to be removed from the rear. Follow this YouTube example-- it should be similar to your dryer even though it may not be exactly your model. Be sure to notice wires and cable connections, and be sure to reassemble just as you disconnected. It's wise to take photos as you go so that you can recall how parts and wires go back together.
If the heating element is severed, obviously it will need to be replaced. If the mounting insulators are in good shape, you might choose to just replace the wire. As in this video, some skill is needed to disassemble the heating wire from the mounting plate. If one or more insulators have been damaged, the entire heating wire sub-assembly should be replaced. Or, as listed above, the entire sub-assembly can be purchased, which includes the two temperature sensors. This will simplify the project (but cost a bit more). The temperature sensors should be in normally-on condition, going to open state at temperature set limit. You can check the sensors with an ohm meter. If either is open at room temperature, that sensor has failed and also needs to be replaced.
Make the repairs warranted by your investigation, re-assemble the heating sub-assembly being careful to match photos you've taken, re-install in the dryer, re-assemble the dryer vent, door and top, re-connect the dryer to its electrical source, then test the dryer. The temperature should quickly rise within the dryer drum.