Alternator not working?

Yesterday my radio began randomly cutting out while driving. While still driving, I started turning my headlights on/off to see the impact and as a result every 3-4 times this would cause the radio to cut out again, rpm guage to drop and the ABS light to come on. This morning my car wouldn't start (completely dead). Turned on head lights for kicks and they were just fine. So tried to start car a second time and it worked! Weird. So by turning my lights on, that allowed my car to start. Noticed my radio lost all of it's programming overnight and now is prompting me to re-enter the mfg code. Looking for ideas to understand how these items could be connected and what could cause this type of malfunction. Thanks!