I didn't bother to read all of the posts, but did you try switching to one of the other characters? I had an instance once in the Onderon mechant quarter that my main character just fell into the ground, down below the ground. I could see everything from below, I could see into all of the buildings, it was a cool view, but I was trapped. I tried for about 5 minutes to get out of the "hole" by running back and forth, side to side, but nothing worked so I tried switching to a helper character and that teleported my main character out of the "hole". That's the only advice I can give.