Clean your keyboard. Sometimes a tiny piece of dust may prevent a good key from being pressed normally.
Remap your keyboard. On Windows you can use Keyboard Layout Creator. On Linux you can use xmodmap. This way you will be able to enter symbols from the broken key using another key.
Use an external keyboard.
Buy a new laptop keyboard. They are not expensive, and with care you can even replace it yourself (if you don't have guarantee anymore; unfortunately, laptops are not easy to open). Otherwise, visit a service center.