Locate the source of the damage or where the couch is broken. Run your hands over the arms of the couch and along the back, shaking the frame and feeling for any loose connections. The couch should wobble slightly when you find the break.
Remove any cushions from the couch and examine the fabric covering the damaged spot. If the fabric features seams, gently run a utility knife across a seam, popping the threads loose. If the couch uses upholstery staples, slide the tip of a pair of pliers under each staple and gently pop it loose from the fabric. Peel the fabric away until you have access to the frame. You might need to pull off stuffing or padding.
Examine the frame carefully. The frame forms the support for the couch and consists of individual wood planks and pieces connected with screws. Locate the broken or damaged plank within the frame. Unscrew the screws holding the broken piece in place. Set aside the two parts of the broken piece together, lay them together, and measure the width, height and length of the piece. Purchase a new wood plank in the same size.
Place the new wood plank in the exact same location where the old piece was. Screw two-inch wood screws through the new plank and into the frame, attaching the wood to the couch frame. Attach two wood screws through both ends of the wood and wherever it touches the frame.
Cover the repaired area with the original stuffing or padding, if you removed it. Pull the fabric back over the couch and push down with your hands, holding the fabric in place. Staple the fabric to the frame with a staple gun, which keeps the fabric from pulling away.