It is not uncommon for a woven garment to catch on a sharp object, causing an unsightly snag in the material. A snag characteristically has a single, long loop of thread dangling loose with the fabric slightly gathered or puckered on each side of the long thread. The pulled thread causes the distortion in the weave of the fabric. Fortunately, you can fix the snag so that it is no longer visible, and continue to enjoy the garment.
Pull the fabric along the grain line to work out as much of the snag as possible by pinching a small amount of fabric on each side of the pulled thread and moving your hands apart. Make sure your hands are aligned with the same thread on opposite sides of the snag. Rotate the fabric 90 degrees and repeat the pinching and pulling motion, working the pulled thread back into the weave.
Repeat Step 1, but with your hands about an inch farther away from the snagged thread. Keep repeating this process, moving your hands further from the snag, until your hands are at the edges of the garment.
Rotate the fabric 45 degrees and repeat the pinching and pulling motion, working the threads on the bias.
Lay the garment on a flat surface. Use the point of a pin to continue easing the thread back into the weave of the fabric by lifting a small amount -- less than 3 mm (1/8 inch) of thread from either side of the pulled thread. Keep doing this, moving farther from the snagged thread by about 6 mm (1/4 inch) each time.
Repeat Step 1 to 4 until you have worked the pulled thread back into the fabric as far as it will go, leaving only a small tail of thread dangling.
Insert a long straight pin from the right side of the fabric through the spot where the tail of thread emerges. Move the tail of thread around the head of the pin so that as you pull the pin through the fabric to the other side, it will bring the thread along with it
Repeat Step 1 if necessary to smooth the weave of the fabric.
Lay a damp cloth over the snagged area of the garment and press with a warm iron to further flatten any remaining distortion or puckering.
You may wish to buy a tool called a "fabric snag repair needle" or use a very small crochet hook instead of the head of a pin. This tool may make it easier to grab the thread and pull it through to the reverse side. You can find this needle in fabric stores or online.
Never merely snip off the long thread of the snag. This will cause the fabric to unravel resulting in a visible hole or "run."