Is it possible for your teeth to just fall out of your mouth?

No: You would need to have years of neglect, and severe periodontal disease before a tooth would come out on its own. Even then you would lose one at a time, not all of them together.

Are you sure?: It's possible but unlikely. More likely is that there is a lot of decay in your teeth and the crowns - the visible parts - are breaking off. The roots might still be there. This could cause infections. You should seek dental care.

Only with help: Not by themselves, only with: 1) traumatic injury 2) severe tooth decay. 3) severe gum disease. If a tooth came out, you need to get to a dentist now as the infected root could still be in the gum.