1996 geo tracker will not come on the headlights and radio work but the car wont start what could be wrong could it be the starter or the alternator?

The starter is where I'd go first. I've just recently just had this problem with my '97. The tow truck driver clued me in when he had me turn the key and he rapped the starter from the top and I started right away. I was told that the starter is bad and after that I believed him because this has happened before and I've not had an answer until this last guy. He was my savior that day.