Well we don't have enough vehicle history to jump to that conclusion just yet & I'm not a tranny guy, I know just enough about em to be dangerous!!!! lol

You likely need input from a Ford tranny tech.

Is the OD light on, or flashing????

Did you ever try turning the OD OFF, by pushing the switch on the end of the shift lever, until the OD Off light in the dash comes on, then trying to shift into gear????

This is supposed to deactivate the torque converter lock up solenoid/clutch, so maybe exercising the OD switch would wake something up?????

Has this vehicle had any tranny problems or repairs before this event????