Get a multimeter with a continuity tester.
Disconnect the two wire plug from the alternator, disconnect the four wire plug from the regulator.
Place one tester probe on the connector that connects to the F terminal and the other probe on the F terminal of the two wire plug, the meter should show continuity. Do the same with the wire that goes to the terminal marked 2 on the regulator and the other wire in the two wire alternator plug.
There has to be continuity between the four wire plug and the two wire plug in order for the regulator to send current to the alternator field.
If that checks out OK get your regulator and alternator checked at the parts store.