How much is a 1979 silver half dollar worth?
I had to change your wording because the word "your" implies that one of us in the answers group has such a coin, which we don't, LOL!
Anyway, the U.S. did not mint any silver half dollars in 1979. All were made of cupronickel - look at the edge and you'll see the copper core. As such your coin is a regular circulation issue worth face value. Fee free to spend it on a newspaper or candy bar.