If the key is broken off in the keyboard, or the keyboard is otherwise damaged, you have no choice but to replace the keyboard. The good news is that this is not difficult to do, but it is fairly time consuming. Depending on the laptop, it may be faster to replace the entire top case, but that will also be more expensive.
the best and fastest way to fix a stuck key on laptop is to use a can of compressed air. Normally it's enough to spray a little bit of air on the key and it becomes normal again. If it doesn't work, then you might have to disassemble the laptop and clean the area below the key.