Boss disapear after quit game

Hi there, 

Don't know what happen exactly but yesterday at the end of the lake temple, i was fighting the boss but didn't beat him yet, i saved the game and quit. today, when i'm running to him ( them ) they're not here anymore ... I mean, the door is open, there is the teleporter, but no bosses and no chest ... So i'm stuck 

How can I fix it ? 