My dryer will not heat. Have replaced the heating element and the thermostat. 
Here are your parts
Replacement parts for WHIRLPOOL WED6400SW1 29" ELECTRIC DRYER | AppliancePartsPros.com
Here is a service manual.
Whirlpool 8178584 Cabrio Dryer Service Manual - ApplianceDigest.com
The first thing to check is the power.
The motor will run on half the line but the heating coil requires the full 240 volts.
Try flipping the breaker off/on slowly a couple times, sometimes you can loose half the line without actually tripping the breaker.
If this does nothing, check 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 the wires at the terminal strip in the machine to make sure none are loose or burned out
If OK
Check the power at the terminal strip.
Be careful as 240 volts is lethal !!!