answer:One thing to check is if there is a lot of lint or dirt interfering with the grip of the Velcro. You can use a toothbrush on the rough side of the Velcro to try to clean it out. Velcro is easily found in sewing and fabric stores. Also, in large craft stores, and probably even Walmart if it has a sewing section. You could try to “seem rip” it out, and sew a new set in, but probably better to give it to shoe repair to do it. Edit: It might be glued and sewn. That might be more tricky. Still, a repair shop should be able to do it I think. I’ve had shoe soles glued and sewn at a shoe repair shop.