The Restore Project tool restores a project from a backup file made with the Backup Project tool. The backup files will have a .PRJ extension. Backup files are forwards compatible, meaning they can typically be restored in the same or more recent versions of the software, but cannot be restored in earlier versions of the software.
In Project Manager, right-click a workset and select Restore from the pop up. This means a workset must be created before restoring a project backup.
Select Project Manager > File > Restore
Error - Unable to restore project, project's database version is newer