First check your fuses to be sure that lack of power is not caused by that. Next go to the fan motor and check to see if you are getting 12v at the harness, that plugs into the blower motor. If you have 12v and the motor isn't running replace the blower motor. If you don't have power check the blower motor resistor, it controls the fan speeds. If you are getting power into it but not coming out to blower motor replace the fan speed resistor. If both the resistor and blower motor check out ok, move to the speed control switch on the control in the dash.