Question

What is the best course of action to follow should you lose your train of thought during your speech?

Answer 1

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

Answer 2

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.