95 escort with no over/drive

My 95 escort does not shift into over/drive and I was wondering if anyone has any ideas why, before I go looking around under the car.

Thank you.

is it getting to operating temperatures with this cold weather....(provided you live somewhere north). A cold engine will not shift into overdrive. Also there should be a little cover just beside the base of the shifter. pop it open and press the button with a screw driver. i think this has something to do with overdrive but cant think of it right now.