Northern thanalan is empty because they nerfed dark devices into the ground and they buffed dungeon XP considerably. So at 47, most people are leveling in the dungeon aurum vale.
Now as for not remembering how to play your class you could do low level duty and guild hest roulette. At the end of both of these you get a nice chunk of XP and you get to do it in a low level environment which is perfect for learning.
If you have any specific questions, though, about your class or the leveling/gear progression, feel free to ask away. I'm sure we'd be happy to answer.