1989 ford probe issues?

hello, my name is alex and i have an 89 probe 2.2L fuel injected and when i go to start the car i can only pop up the headlights to the car, but when i try to start it it wont start, and there is no power at all inside the car just the headlights? what can cause this problem? tried to replace the, starter, that was good, and then i went to the alrtornater, found that a couple ground wires were out and live, so i went to the junkyard and got a new one, after that i had found that my alternator belt was not where it was supposed to be, it actually came off during the time, so i put a new one on