Ive just gone to close this door and it has come out of the groove and i dont know how to put it back.The lip is too high to lift it over.Ant ideas as its freezing
Try using a garde spade as a lever - a brick or two under the top of the blade at the back to make the handle about horizontal and then you will find you have enough leverage to lift the door. You will need another pair of hands to actually push the door back over the lip, though. (I'm assuming it has fallen towards the outside)