won't start only clicks

What is your question?

THe van is very old only but always starts. After my son left the key on the battery went dead. We jumped it, changed out a battery terminal that was bad. Thought maybe it was the starter and put in a used one, only clicking no start. It also before this would shut down on the freeway like someone turned off the key. very anoying. Then it would always start. Now, only clicks.