On some of the newer dryers they have sensors that may be covered in lint and therefore are overheating. My dryer has a sensor behind the lint bucket and when it get's full of lint, it stops heating the clothes. Could also be a bad heat senor that is stuck in the open position. These are small silver or black round disks with two ears with screws through them. They are most likely positioned near the heating element. They typically have two terminals with wires attached.
If you have access to a simple continuity tester you can check to see if these are bad by simply removing both wires and see if your buzzer goes off. Always touch the tips of your probes first before hand to verify you are getting a tone from your meter. If you get a tone it means the sensor is closed and working. If there is no tone from your meter the sensor is in the stuck open position which does not let the heating element get hot.
These are safety devices to protect you dryer from getting too hot and catching fire. Never bypass a safety device. High Temp sensors are rather inexpensive and can be replaced for a few dollars from your dryer dealer or appliance repair center.
Good luck and all the best ~~ dgicre