To repair wood siding, inspect the damage and gather tools and materials like a hammer, screwdriver, nails, and wood filler. Remove damaged boards and replace them with new ones. Fill cracks and holes with wood filler and sand them smooth. Reattach loose siding with nails or screws. Seal seams with caulk to prevent water infiltration. Protect the siding by applying paint or stain. Wear safety gear and handle chemicals cautiously.