Hi,Stephanie. I'm not sure that I can help but I have a couple of questions that might help others. Is the area under the pictures lighter or darker than the surrounding walls? What kind of paneling is it? Solid knotty pine? Plywood? How thick? Real wood or a picture of wood?
In an out-of-the-way location, try washing with baking soda mixed pretty thickly with water and then rinsing. Try to keep the wood as dry as possible and only try it on smooth wood. It will be hard to get the white grains of baking soda out of textured wood so don't try it on textured wood.