Yeah, that’s what happens when a timing belt breaks.
This doesn’t make any sense. It literally cannot start if it won’t turn over.
This is OP’s last statement on the matter. Of course, he then said the car started but didn’t turn over, so I think we have some confusion in the sequence of events.
I suspect, unfortunately, that he means the car’s engine died at 75mph, then he pulled it over and turned the key to “off,” which was superfluous because the engine was already off, forever.