Ok. I'm at the castle, after fighting all the guards, trying to get to the "Larder", I see a door that goes forward, and its locked. I tried looking for a key and I can't find it. I only got the sword and armor from the treasury.
Are you talking about the hallway that the larder is in? The door at the very end? Some of the doors in Castle Cousland are only openable if you have Lockpick, and other than Family Sword and Shield in the treasury, nothing else in the castle matters. It's like, elfroot and copper. No big deal.