I put a new thermastat on and the unit does not work? Where is the reset button on the furnace?

Model number?

I really doubt that there is a reset. I would be more inclined to think that

You blew the fuse on the circuit board.
You wired the thermostat wrong.
You blew the transformer by short circuit the wires.
Check all circuit breakers
Blown circuit board.
Wires loose or rubbing behind thermostat.