Who do I ask for a reference after a layoff? after 11 years as a copywriter

The company closed and I am not sure how to reach former colleagues. I worked as a copywriter before this. HR only confirms titles and dates. How do you ask politely?

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

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