Unfortunately, Map creations (and all other additions to the game such as presets, objects, items, textures, etc) are all stored within the FH folder. If you deleted your folder when uninstalling the game without creating a backup there is no way to get those files back. The same can happen if you're reinstalling the game with a fresh folder, the only thing that comes with the game is the default maps, items, objects, markings, etc.
Sorry to hear about those files! I tend to upload all my creations to dropbox or google drive just in case (if I were to leave or need to reinstall).