Yeah, the same problem occured with me. Luckily, I had a save just before it happened. What you should do to aviod that bug is to remove Ammon Jerro from yout party before entering CK Courtyard. Then he would initiate the converstaion which will in turn reveal Nonolath's Valley to you.
If you can't go back, then you could try to use the .xml file and enter a command that will reveal its location on the world map. But be warned that doing so could crash your game and make it even more bugged than before. By the way, I'm not really sure what that command is. You have to refer to prior commands that reveal other locations such as the one in the start which reveals the Swamp Ruins. It should be near the top of the .xml file.
The file is located in your savegame folder.
Love is just a chemical. We give it meaning by choice ~ Eleanor Lamb, Bioshock 2: Sea of Dreams