Chairs that are often moved around can mar wood floors. Prevent this by putting rubber or smooth metal tips on chair legs. Lay a clear plastic mat or an area rug under a rolling chair.
If a waxed floor is lightly scratched, a liquid solvent-base wax or paste wax may disguise the marks. Otherwise go over the area with fine steel wool and a solvent, such as mineral spirits, then rewax. If a polyurethaned floor is hazed with scratches, you can revive it with a light overall sanding and a fresh coat of polyurethaned.
To blend a deep scratch with the surrounding wood, remove old wax with solvent, then fill the scar with a tinted wax, wood stain, a wood-toned crayon (available in hardware stores), or matching wood putty (sand the wood putty when dry). If the floor has been finished with varnish, shellac, or polyurethane, touch it up with the same finish, feathering your brush strokes to blend with the surrounding finish. If the floor has been treated with a penetrating finish or wax, apply a fresh coat.