Hi Colin
Is this a standard folder, a sub-folder or a folder originally created by you under the virtual My Folders name? Did you inadvertently delete the folder? If so it'll be in the Trash folder. The presence of sub-folders in any folder including Trash is indicated by a right facing chevron in front of the folder name. You can move or drag and drop back to where you need it to be.
Using a desktop browser with laptop / notebook. If necessary toggle the Folder view to show icons with folder names. The toggle is a book-like icon bottom left of the screen. You'll see in the Folder view, to the right of My Folders, is a plus symbol. Tap that and you'll be able to add a new personal folder.
In the standard folders the action to add a new folder is via the triple dots ellipsis icon (Actions on folder) to the right of the folder name.
