When carpets become damp, particularly if sticky liquids are spilled, the fibers can become matted and flattened down. If this has happened to you, ensure that the area is thoroughly clean and dry and no residue remains hidden in the fibers. Then, go in with a stiff brush or carpet rake and make the carpet fluffy again. You may need to add a little bit of water to loosen the fibers initially but do so sparingly. You may also need to repeat this a few times to see lasting results.