I would be very doubtful that either your alternator or starter is your problem. I don't have a wiring diagram in front of me, but I'd guess you need an ignition switch. In most cars, its the only thing common to the electrical systems you mentioned. The switching power for your window relay, headlight relay, and starter relay all come from the ignition switch. The power for your guages, radio, and parking lights do as well.... If your igntion switch is broken, the situation you describe can certainly happen....
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