If I remember correctly, he's in the very top right of the screen. Go to the lake and follow it upwards.
If he's definately not there, then... have you patched the game to the latest version? I have no idea whether that it relevent in anyway to your problem, but it's something I would check on if I was in your situation.
Highlight to read - <span class='standouttext'>Spoiler : </span><span class='spoiler'> Failing that, and if there's no other solutions from the people here, then remember that you do not NEED to visit the dragon to continue the game if you have the skill which allows you to turn into a ghost. Just go to the lake, turn into a ghost and go across. If you don't have that skill then I guess you could use a save game editor to give yourself the skill. </span>
All that is a last resort. Hopefully someone else here give you a solution which allows you talk to the dragon.
