6. Reassemble the frame. I found the best way to fix a broken frame like this is to pre-drill a small hole at each corner (to keep the wood from splitting), then drive in finish nails with a hammer. Use a nail set to drive them beneath the surface, fill with wood putty, then sand smooth when dry. Protect your work surface with a drop cloth, then paint two coats of primer and 1-2 coats of paint, letting dry between coats. I painted the front and back for a more professional look.