Understanding to your people that you've lost your train of thought from there, make fun of the situation, say let's see, where was I in a funny manner
Personally, I would address the problem, explaining to your audience that you've lost your "train of thought" from there, make fun of the situation, say "let's see, where was I?" * recieve an answer from audience * then continue one.
To sum it, make fun, and a light hearted joke about it, and continue to your best ability.
