I've got some popcorn that I've had for a while, and when I try to pop it, a lot of the kernels remain unpopped. Is there anything I can do to revive it, or does it go in the compost?
I store my popcorn in the freezer in an old mayo jar with the lid tightly screwed on. As Michael says, dud popcorn has lost moisture. Add a tablespoon or so of water to the jar and put in the fridge (not the freezer for this part) a few days and see if that helps.
Storing uncovered in the fridge or freezer will remove moisture if you have a frost-free refrigerator.