Cant get to northrend

So as the title suggests , i cant get to northrend.. I was there doing some leveling. etc. until i went to [The Nexus]
when we finished it we couldnt leave the instance by the entrance cause it said something like:
"You need to have WOTLK expansion installed to enter this area".
well i somehow hearthstoned out later and when i tried using the ship back to northrend, it gave the same error and stranded me on westfall
warmane please fix soon :)

Looks like a problem with your client. Tried deleting and downloading new one?