Thread the needle with a length of thread approximately 24 inches (~61 cm) long and tie a knot at one end of the thread. For more details see Needles and Thread.

The pictured repair uses contrast thread for visibility, but matching thread will make this repair almost invisible.

From the backside of the seam, pierce the needle through to the front, overlapping any existing stitching by at least 1/2 inch (~13 mm).

If the seam doesn't have a front and backside, choose either.

Pull the thread through until the knot lies flush against the fabric.