Who do I ask for a reference after a layoff? - what worked for you?

The company closed and I am not sure how to reach former colleagues. This is my first time dealing with any of this. A colleague offered to vouch for me. Is a client acceptable?

A client reference worked well for me. It shows you deliver outside the company too.

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