As keyboards get old they have a tendency to loose their spring. Most keyboards (laptop and desktop) rely on a combination of rubber springs and somewhat fragile plastic scissor clips. First, we never recommend you taking your keyboard apart to resolve the stuck key. It can lead to disastrous results and you needing to replace an otherwise healthy keyboard.
There are several things you can try to do to fix a stuck key or two. Check out the article at PC World for some great tips on resolving your keyboard frustrations at I’ve got a dead key on my keyboard.