Try wiggling your ignition key. Sometimes with age, the ignition switch will not return fully from the crank position. There are separate contacts in the switch for blower power.

Check the voltages at a connector above the brake booster which has heavy red and black wires and a thinner yellow wire. You should have 12 volts between the black and red wires. The yellow is the fan speed control voltage coming from the pushbutton unit. It should have about 1 volt for low speed to about 6 to 10 volts for high.

If voltages are correct, then you have a problem with the fan control module (located below the blower) or a bad motor or both. Remove the windshield wiper mechanism and remove the blower cover. Disconnect the blower wires and connect 12 volts directly to the motor to see if it runs.