[jhv48]

Before you get all involved in searching for an electrical problem, flip your fan switch on when your ignition switch fails to start the car. If the fan comes on independently of the the ignition switch working you have narrowed down the problem to either the ignition switch itself or the starter/solenoid.

Now, one by one. Check that the wires to both the ignition switch and the solenoid/starter are tight. That could be the easy fix. Then, if the wires are tight, in order to eliminate the starter/solenoid, you must crawl under the car and bypass the ignition switch by placing a screwdriver across the two poles of the solenoid (or use a remote starter if you have one to bump the starter, less sparks). Make sure the car is in neutral and just touch the poles briefly to see if the solenoid engages. If the starter engages and spins, then it's the ignition switch. Replace it.

If the shorting out of the solenoid doesn't produce a starter engagement, then your solenoid is bad. Rarely will it be the starter.

My bet is a loose connection to the ignition switch or solenoid or a failing ignition switch.

These are the easy steps. If no fix, then we have to go deeper.