There can be many reasons for no power, the breaker may still actually be tripped. If all you did was turn it off and then back on again, that will not always *reset* the breaker, you have to turn it off, then *push it OFF* to reset it in many cases.
You could also have a wire burnt off at a junction box at the furnace or before that. You will need a multi meter to do some tests. ($30 at a hardware store for a good one).
It is possible that you actually do have power to the furnace but that a fuse on the printed circuit board is blown, or the 24 volt transformer is bad.
If you want help in trouble shooting this, please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to be taken from straight on, in very good light.
You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here.,Include a picture of the thermostat wire connections to the printed circuit board in the same area.
If you have an error code showing, tell me what the code read out is on the wiring diagram or a sticker next to the diagram please.
If there is no paper clip-icon, look for the '+attachfiles'link at left of your send button.
I can mark it up with trouble shooting instructions.
We can go from there.