Getting references after a company closes - what worked for you?

I worry a reference will only confirm dates of employment. I have been trying to stay organised about it. I have one former client who liked my work. How do you ask politely?

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

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.