Check your mini-map. Are there any green crosses in or near the room which could be the instructor? You did talk to him before to get the quest, correct?
If he got into / through a wall, which can be caused by alt-tabbing out of the game, you may be able to get him back by more alt-tabbing, or by;
Teleporting anywhere (via hex editor)Do you have any previous saves you can revert to, to get him back without having to redo too much?
