First Aid for Wood Flooring
Scratches or stains beneath the surface of a penetrating stain and wax can be treated. Here are some ways to repair damage. 

Dried Milk & Food Stains:  Gently rub with a damp cloth. Rub dry and wax. When removing stains, begin at the outer edge of the stain and work toward the middle. 

Water Stains or White Spots:  Rub spot with #000 steel wool and wax. If this fails, lightly sand with fine sandpaper and clean the area using #00 steel wool and mineral spirits or a wood floor cleaner. Stain, wax and hand buff after the floor is dry. 

Heel Marks:  Rub in a small amount of wax with fine steel wool and hand buff. 

Mold: Rub with a wood cleaner. 

Oil & Grease Stains: First rub with high lye content kitchen soap, or saturate cotton with hydrogen peroxide and place over the stain. Then saturate a second layer of cotton with ammonia and place over the first. Repeat until the stain is removed. Let the area dry and then 
hand buff. 

Dark Spots & Ink Stains: Try the water spots treatment. If the spot remains, apply a household bleach or vinegar and allow it to soak for one hour. Rinse with a damp cloth, wipe dry and smooth with fine sandpaper. Stain, wax and hand buff. 

Wax Build Up:  Strip the old wax away with odorless mineral spirits or a wood floor product made for stripping wax. Use cloths and fine steel wool to remove residue. After the floor is dry, wax and buff. First aid for surface finished floors If the scratches or stains are in the finish, it is probably a surface finish. 

Scratches:  Repair with a touch-up kit made for urethane finishes, available from wood flooring retailers. 

Food, Water or Dark Spots: Use a cleaner developed specifically for urethane finishes to remove the spot or stain. More stubborn spots may require additional scrubbing with the cleaner and a wood flooring scrub pad made for urethane floors. 

Greasy Spots:  Rub the grease, lipstick, crayon or oil with a urethane-specific cleaner. 

Cigarette Burns:  Most burns can be treated with a touch-up kit made for urethane finishes. Rub with sandpaper, stain and refinish. For burns that reach deep into the wood, individual plank or parquet boards may need to be replaced. 

Chewing Gum, Crayon, Wax:  Again, apply a plastic bag filled with ice to the deposit until it becomes brittle and crumbles off. Clean the area with a product made for urethane finishes. Always use the wood flooring manufacturer's cleaning, repair and finish products when known.

Source: The National Wood Flooring Association