I put cinnamon in the water I water with, just a little shake of powdered cinnamon in a pitcher of hot water and stir. I do this all the time and it works very well against damping off and fungus gnats.
You want to be careful if putting the cinnamon on the soil and especially if it would touch the plants. Too much cinnamon can burn the plants. It doesn't kill them (at least I never have), but it can leave whitish burned looking spots.
If your little seedlings are already flopped over, then they can't be saved. Damping off can be prevented, but not treated.
Be sure not to over-water and provide good air circulation, both of which help against the damping off.