If you're still playing (na xbox 360), this may help: Don't save over an old save game, always make a "new save game". If the boss fight you are talking about is in the mine tower, you are cautioned not to go in there the first time you try to go through the gate. You can enter and save Williams inside later because you return to this area later at a higher level. Could you clarify where in the game that the doors are that you can't find? Some exits are locked until you find certain things in some areas. Don't give up on this game, it's gets better as you learn more about it.
