Please keep unused backups on a separate pen drive so you can revert to the backup if required.
You will need to install an old version of Manager to update your database in two steps. To get the intermediate version see Restoring data issue - #2 by Patch
If you have installed a newer version on your local computer, you will need to uninstall the new version prior to installing the intermediate version. When you then try to open your local copy of your business file it will say it has already been opened in a later version but convert it so it’s compatible with the later version anyhow. Alternatively import a new copy of your un-used back up.