I have a 2006 Ford Freestar SEL?

2 weeks ago as I was driving I heard a blast of air then my van wouldnt go. It was still running but wouldnt kick in to gear so i coasted into an approach. I put it in park then reverse n each of the other gears but it wouldnt go. My husband checked the transmission fluid and level and said it was fine. Does this mean I need to replace the whole transmission?

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