Help, my plunger isn't working!

As I tried to fill the sink with water the other morning, I realized that my plunger handle was not making the stopper go up or down. This in an important thing for it to do if I am to retain any water in the sink. Try as I might, I was unable to make my attempt at plumbing work. Apparently, the problem was not where I had originally anticipated and it wasn't in an area I could easily reach. What's happens next in the bathroom faucets repair dilemma is a godsend. My son says as he enters the bathroom, "Mom, I'll fix it. It's done that once before and I know how to fix it." Thank goodness he has been paying attention in his classes in AG Mechanics!