check to see if you have a wire, smaller gage from positive terminal, some have a separate hot wire to the acc. key, mine corroded lossing connection and some have fusable links in them.
Dead battery or corroded battery connections.
Check your connections. bad connections can make a battery not charge or not power the phone.
Poor cable connections to the battery , or dead battery
Check the battery cables for being clean and tight. The smaller red lead goes to the power distribution box. The connections there are bad about making good contact.
Corroded battery post connections, defective battery, or defective starter.Corroded battery post connections, defective battery, or defective starter.
Dirty or loose battery connections.
Check the battery connections.
If you have no battery then you have no power.
Defective alternator, dead cell in battery, something on pulling power from the battery when the vehicle is idle, corroded battery cable connections, or loose alternator drive belt.
dead cell in the battery or something is on pulling power from the battery.
Check your starter, and all power connections.
Any time you have no power to the headlamps I would concentrate on a bad battery cable or ground cable or battery connection. It works now once in a while, but if you don't get it taken care of, it will soon fail totally. Trace and clean all connections starting from the battery back thru all connections and DON'T skip any that "look good".