Who do I ask for a reference after a layoff? - first time posting

The company closed and I am not sure how to reach former colleagues. This is my first time dealing with any of this. I have one former client who liked my work. Who did you use?

Ask former colleagues and supervisors in a short message and give them a summary of the job you are applying for.

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