For sweaters and jackets, if a snag occurs or threads pop out, the quick fix I use is to take a needle or pin and poke them back into the material. If possible, try to weave/loop the thread through several layers to kind of anchor it so it won't pop back out so easily. It takes a bit of patient maneuvering, but worth it in the long run.
Another way is to stretch the material in all directions, to get the thread that sticks out to go back in. If necessary, while stretching, gently scratch the area, applying pressure with a fingertip to help ease the thread back in, which also serves to smooth out that area and hopefully make it look as if there was no damage at all.
I usually use a combination of the above to much success. If all else fails, then I trim the offending thread, not flush with the fabric, but leaving a bit to compensate for the effects of the next wash/cleaning.
Linda H.
July 2006