A model number may help oters help you.

Did you just look at the breaker or did you shut itoff then back on.
Sometimes you can loose half the line without actually tripping the breaker.

Another common cause is the thermal fuse. It is usually mouted on the blower assembly.

Unplug the unit and check the fuse with a meter should be 0 ohms.

Jiggery Pokery method is.
Unplug the unit.
Remove both wires from the fuse, short them together and tape them up so they will not short to the frame.
Plug the unit in and give it a try.

If blown, replace the fuse ASAP as it is a critical safety device re: prevents lint fires which can turn into house fires.
Also clean/check your vent system as that is the most common cause of it blowing.

Other common possibilities are the door switch or start switch.