In the MFT (Master File Table) in NTFS (standard DoS configuration), all files and folders are marked as a folder or file, and they are marked as belonging to a “parent”. So say you have a folder with a bunch of files within it. Those files are its “children”. For those files to become “lost”, let us pretend the user deletes those files and then deletes the folder itself. The user then creates a new folder. The entry in the MFT for the old folder is overwritten. So it, the original “parent” folder, and its entry in the MFT, are gone. But its “children”, while deleted, have not been overwritten and their entries are still in the MFT.