Here are the parts
Replacement parts for WHIRLPOOL LER5848EQ2 | AppliancePartsPros.com

Here is the wiring diagram
http://www.servicematters.com/docs/wiring/Wiring%20Sheet%20-%203401725.pdf

[COLOR="Blue"]I have power (120 v) to all 4 red wires on the element and the thermostat.
Any ideas as to why it do'nt heat.[/COLOR]
Could be that you have a power problem.
The heater runs on 240 volts and measuring the voltage in reference to Neutral will just confuse you as you cannot tell which side of the line you are measuring.

First try flipping the breaker off/on slowly a couple times. Sometimes you can loose half the line without actually tripping the breaker and the heating coil requires the full 240 volts.
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 the wires at the unit's terminal strip to ensure they are properly connected and none of them have burned off
If OK
Plug the unit in and check the voltage at the terminal strip. This is just in case you have a bad line cord.
[COLOR="Red"]Be careful 240 volts is lethal.[/COLOR]
If OK
Unplug the unit and check the heating coil and thermostats etc. for continuity.
Heating coil, should be 10 ohms approximately.It is not unheard of to get a bad replacement part.
Thermostats and thermal fuse all should be 0 ohms.
I could not find the thermostat you replaced using the given part number.
The thermal fuse for the heater element is Item 9 in Section 3 of the parts.
The other thermal fuse is on the blower but it kills power to the motor.

Be sure to disconnect one side of and device you are measuring this prevents reading an alternate/parallel circuit path. Also use your most sensitive ohms scale.
There is a good Sticky at the beginning of this forum on meter usage.