Thanks for taking the time to post here in the Community, kresso.
Yes, you can open your company file in your other version of QuickBooks Desktop. If you keep your company files on a server, just move them back. Here's an article you can refer to for more details about upgrading your company files after switching to a new version of QuickBooks Desktop.
Additionally, to learn more about the backup and restore process, here are the great articles you can refer to:
Should you have any follow-up concerns about this or you need anything else, please let me know. I'm always here to help. Take care!