Got a denial letter for unemployment, what now? - any advice?

I got a denial letter last week saying I left my job voluntarily, but I was let go as a production planner. This is my first time dealing with any of this. My employer's version of events does not match mine, and I have emails that show it. Did you bring documents or only talk?

I printed my emails in order and wrote a one-page timeline. The hearing officer kept going back to it.