References when my manager was laid off too, security officer here

My manager was laid off too and I am unsure who to use as a reference. I have read a lot of threads here and could not find my exact situation. I have one former client who liked my work. How do you ask politely?

I kept a note of my results so my references could be specific. They appreciated it.

Use a professional network to find a former manager. Many will still write a note.