message history on MacBook Pro dissapeared after operating system upgrade

Hello,

I recently upgraded my macOS software to High Sierra on my 2012 MacBook Pro Retina Display laptop. After runinng what seemed like a fairly routine update, when I opened up my computer again, and started messages, my entire history was blank. How can I get the history back? When I google this, the only answers I see are to "Restore" through Time Machine. This is not a current option for me, and I think the messages are still "out there" because parts of them are on other devices, and I can see the archive, chat.db etc. files in my library. I just don't know what to do with them. How to connect/resynch?

As a sidenote, messenger is working (I was able to receive a test message).

Thanks!