Here is the tech sheet
http://www.servicematters.com/docs/wiring/Tech%20Sheet%20-%203979705.pdf

Could be one of the components you replaced has failed.
You will need a meter to check what actually is blown.
Probably the thermal fuse (cut-off) in the heater circuit.
When you replaced the components did you clean/check your vent system?
I am assuming that the thermostat you replaced was the high limit thermostat.
It should have regulated the temperature so that the fuse did not blow.

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.
Thermostats and thermal fuse all should be 0 ohms.

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.