Wooden doors are prone to dents, dings, scratches, holes and any number of other surface defects--all of which are easily fixed. Holes in wooden doors can vary in size greatly and are caused by various means; however, the method used to fix holes, gouges and dings is the same for every situation.
Take the door out of the frame and lay it flat on a pair of sawhorses with the damaged side facing up.
Remove any paint and other wood finishes, dirt, debris and other foreign matter that may be present in or around the hole. This can be done with a regular screwdriver or wood chisel or by drilling the hole out to expose bare wood. Exposing bare wood allows the wood filler to adhere to the hole more effectively.
Open a can of wood filler and remove a small amount at a time with a putty knife. Spread the wood filler over the hole and press it into place to completely fill the void. Scrape the wood filler with the putty knife so it is level with the wood around it. Allow the wood filler to dry. If the wood filler shrinks or forms a depression after it has dried, add more wood filler and allow it to dry.
Sand the wood filler with an electric sander so the filler forms a smooth, seamless transition between where the hole used to be and the wood around it. Remove any residual dust with a tack cloth.
Apply a coat of primer over the repaired area and allow the primer to dry, then add two coats of paint to the repaired area and allow it to dry as well.
If staining the wooden door, apply wood stain to the repaired area and allow the stain to sit on the surface of the wood for a couple of minutes. Wipe the excess away with a dry cloth rag. Allow the stain to dry according to the directions on the container. Then use a foam brush to apply two to three coats of polyurethane over the repaired area and allow the polyurethane to dry.
Rehang the door in its frame.
If the door is to be stained and clear-coated after the hole is filled, use a stainable wood filler to fill the hole.
Some wood finishes require adequate ventilation during use and drying. Follow all application instructions and read all precautions and warnings before using wood-finishing products.