Usually folders like pictures and documents show up with an icon in nautilus. Since I have a 1TB hard drive for storage I decided to put the folders there instead and create a symbolic link to my home folder. At first the folders had icons just like before, but not anymore. How do I bring these icons back?
One thing to try is checking your view settings, and checking your preference for display. The main options are List and Icons, maybe 1 or 2 others. Open Nautilus to the folder in question, and try those.
Beyond that, to configure a custom icon, you could create a Desktop Entry file. These are the files Ubuntu uses internally to create visible shortcuts and app launchers. You can make one from scratch, or copy and modify from /usr/share/applications.
Does that help?