Complete loss of brake pedal then all gets normal?

Very rare,very rare issue.
Have never encounter a complete loss of brake pedal then have it come back. 
See if you get Any ABS warning indicator.IF no then

There are really only 2 things that could be involved here if there is no fluid loss. The master cylinder internal leak or and issue in the ABS actuator. Because the are no warning lights for the ABS it is not likely an issue with the actuator. This only leaves an intermittent issue in the master cylinder which would be extremely odd. 

Check properly and inspect,Fluid level in the master cylinder looks good?

If NO,then replace the fluid.

This details will help you.

See below latest solved problems :--------

Truck is hard to start and Emits smoke while starting?

http://schematicsdiagram.blogspot.com/2011/12/truck-is-hard-to-start-and-emits-smoke.html

Engine cuts out at 3000 RPM?

http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html

Car turns over but will not start, only makes clicking sound?

http://schematicsdiagram.blogspot.com/2011/12/car-turns-over-but-will-not-startonly.html

Catalytic Converter glowing hot?

http://schematicsdiagram.blogspot.com/2011/12/catalytic-converter-glowing-hot.html

After getting car washed, check engine light is ON and key less entry not working, tried reprogramming. Also car shows fuel pressure?

http://schematicsdiagram.blogspot.com/2011/12/after-getting-car-washedcheck-engine.html

Fuel gauge jumps from empty to full?

http://schematicsdiagram.blogspot.com/2011/12/fuel-gauge-jumps-from-empty-to-full.html

Why airbag light flashes 7 times?

http://schematicsdiagram.blogspot.com/2011/12/why-airbag-light-flashes-7-times.html

Passenger side Folding Mirror is not operating?

http://schematicsdiagram.blogspot.com/2011/12/passenger-side-folding-mirror-is-not.html

Very low air output on Chevrolet Trailblazer?

http://howtobyme.blogspot.com/2011/12/very-low-air-output-on-chevrolet.html