Within the hinges on the door to the door frame are a bolt nut that adjusts the 'drop' of the door. There is a protective cover over them - remove the cover and then prize out the nut and bolt - move the nut along the bolt towards the end of the shaft (away from the bolt end) and then place the nut and bolt back - this may require a bit of help as the door may have dropped a bit more. Get someone to push the door back toward the hinge and pop the nut and bolt back, then put the cover back on and try to close the door. You will have to check the lower hinges as well and perform the same task. This should do it.
Si, July 2009