My ac stopped working about 3 years ago. The fan stopped working, when I turned the unit on I would hear a humming noise, the fan just didn't work. Now 3 years later , the fan still not working and there is no noise. My ac unit is about 10-15 years old. What are something's I should look at before calling a repair man?

The humming could have been the Contactor(relay). It needs 24 volts from thermostat, which is fed from the transformer in the Air Handler.
You need to verify you have power Out of each Disconnect.
You may have 2 or 3 problems, fan and control wiring are 2 of them. Did Compressor kick in when it was humming?
Was the humming the compressor?