The main causes of keyboard typing wrong character are:
Enabling Numlock and Fn+Numlock keys can cause the wrong character, especially in windows 8 and 8.1
Wrong selection of language
Outdated windows.
You can use an external keyboard to test the laptop keyboard. If all the above causes are checked and the eternal keyboard works well, see a technician of Good Zone Shop and Service for keyboard key repair of Asus laptop.