Minor surface scratches are the easiest to repair because the scratch is in the protective wear layer of the wood floor. Simply clean the scratched area with a soft cloth and hard wood floor cleaner. You must be careful to remove all the grit before using a cleaner on the floor. If not you may add more scratches from rubbing the floor and trap the dirt under the sealer you will be applying. To clean the floor, you can either sweep the floor or use a vacuum cleaner without a beater bar. A beater bar must never be used on the floor since it may cause more gouges or dents in the wood.
If there are extensive scratches, you may want to have the floor screened and recoating. This is done by professional using fine sandpaper that removes the protective coating or wear layer. This process will only remove topical scratches. The process will remove the wear layer which will have to be reapplied. Ask your flooring professional what types of protective coatings are available. Most wood floors are covered with aluminum oxide, which is very hard. When it is removed usually a urethane coating is reapplied. Although this is a protective coating, it is not as good as aluminum oxide. You can replace the aluminum oxide but it is quite expensive and not very floor refinisher has the expertise.
If the color and the protective wear layer have been damaged, you will probably need to have the entire floor sanded and refinished. In this case, both the wear layer and the color will have to be removed and replaced. Often this problem occurs in the doorway, halls and heavy traffic areas. This can be minimized by using area rugs in front of the doorway and heavy traffic areas. This will prevent stones and grit from being ground into the floor. The rugs must be cleaned weekly so that the dirt does not get under the rug and damage the floors.