Need advice on dropping whole party to 0 hp in dnd 5e [closed]

So I’m a new DM running the Lost Mine of Phandelver for the first time, and the party somehow all got dropped to 0 by the ruffians in the Tresandor Manor. They entered the manor through the tunnel that Carp found which leads to area 8. The whole party was level 2. After the battle with the nothic, they suffered some damage and pressed on to to area 10, where they somehow kept missing their attacks and kept taking damage from the drunk ruffians in there. The characters have all passed one death saving throw, so I assume they are considered unconscious. I’m not sure what to do at this point. Can someone give me ideas?