Without knowing what types of files they lost, this might not be too bad. For the first round of organizing, sort by file extension. E.g. Anything with .exe was

Without knowing what types of files they lost, this might not be too bad. For the first round of organizing, sort by file extension. E.g. Anything with .exe was probably Downloads, video files go to My Videos, and so on. A number of apps will organize JPGs into a consistent directory structure based on the date or other fields in the metadata. For the remaining documents, view by x-large icons so your relative can quickly categorize what goes where.