Actions to be taken when Sandbox has been Refreshed
Regarding the refresh of the sandbox, it is necessary to delete the SharePoint record in the XFiles Manage Folder Hierarchy, as the sandbox refresh involves taking a copy of the production.
Since you wanted to reconfigure SharePoint with existing folders and sync all files, you should establish a new connection in your sandbox by specifying a new root folder name.
Following this, you have to migrate all files and folders from the sandbox SharePoint folder to the latest sandbox-configured folder, once the migration is done then it will sync all the files & Folder and you will be able to see it from the salesforce.