Hey there. Sorry, I can't remember what you have to do at that point. It's been ages since I played it through. 
Does talking to you succubus or the Queen not work? 

If you get stuck somewhere I'd recommend cheating from the main menu up to your current point in the game. Hope that works for you!

Check that you completed every mission here (i forgot everyone's names in this game): level up the knightuntill she beats you once, give the money to the shopkeeper, check up on the queen once and complete the mission she gives you (the priest mission). If you did all of that and still can't continue then yes, you need to restart