I had a quest the other day where i had to met a person in there house. I ran in looked all over the place for them but couldnt find them. Eventally i found there was a second floor that could only be reached by going into a closest type room, closing the door and climbing the wall where the door was.
That tricked me up.
Did you see a ladder on one wall? If it's the kind of room I'm thinking of, the ladder would have been immediately to your right as you enter the door. Ladders in Daggerfall do not work the way they do in most first-person shooters. Instead of climbing it in real-time, you click on it the way you would as if interacting with a door or switch, and it teleports you to the other end of the ladder.