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

My manager was laid off too and I am unsure who to use as a reference. This is my first time dealing with any of this. A colleague offered to vouch for me. How do you ask politely?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

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