I have had this happen about two years ago the time stopped advancing so the dryer will not heat. I replaced the timer and it worked again. I have the same problem. They have sent me two timers and they are not advancing either. what could the problem be?

Here are the parts
Replacement parts for WHIRLPOOL REX3514PQ0 29"electric Dryer | AppliancePartsPros.com

Here is the wiring diagram
http://www.servicematters.com/d...0Sheet%20-%208528187.pdf

The time is not advancing in timed dry and so the dryer will not heat to dry the clothes.
The timer not advancing in timed dry should not effect the heating as the timer motor and the heating element use different contacts in the timer.

What is common to the timer motor and the heater is that they both run on 240 volts.
Try flipping the breaker off/on slowly a couple times. Some times you can loose half the line without actually tripping the breaker.
If this does nothing measure the voltage at the plug
L1 to L2 should be 240 volts
L1 to Neutral and L2 to Neutral, both should be 120 volts.
If OK
Unplug the unit and check at it's terminal strip for a loose or burned off wire.
If OK
Check each of the wires in the line cord for continuity.