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Replacement parts for WHIRLPOOL LEC7858AN0 ELECTRIC DRYER | AppliancePartsPros.com

See the attachment for the wiring diagram.

I would start by checking the power to the unit. The heating coil requires thye full 240 volts, everything else runs off of 120.
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.
Do this with the heater off and on.
[COLOR="Red"]Be careful as 240 volts is lethal !!![/COLOR]

I am assuming you measured the voltage using ground/Neutral as the reference. This can be confusing.
Did you measure the voltage with the unit on or off?
If off and the timer set to a mid-scale heating cycle, then L1 to Neutral voltage is probably OK. along with the thermostats and heating element.

If on then you may be reading L1 or L2 voltage, there is no way to tell with a multimeter. If it is L2 voltage then the centrifugal switch is closing but a thermostat or the timer contacts further up the line have a problem.

Easiest way to check these is to unplug the unit and measure each device using resistance (ohms).
Always disconnect one side of any part you are measuring as this prevents reading an alternate/parallel circuit path.

If you find that the thermal cutoff is blown there are other things to check before replacing it.

[COLOR="DarkRed"]thermal cut off switch, high temps switch,[/COLOR]
Both should be 0 ohms

[COLOR="DarkRed"]and the dryer cycle thermostat are supposed to have[/COLOR]
You have to be careful here as it is a 4 connector thermostat.
2 of the connectors are the contacts, they should be 0 ohms
The other 2 are an internal heater, they should be around 7,000 ohms.