Apple or an Apple Authorized Service Provider will service eligible MacBook, MacBook Air, and MacBook Pro keyboards, free of charge. The type of service will be determined after the keyboard is examined and may involve the replacement of one or more keys or the whole keyboard.
How do I replace one key on my MacBook Pro?
https://www.youtube.com/watch?v=kh88cn_rtLo
How much does it cost to replace a key on a MacBook Pro?
about $4.95 per key plus shipping charges Click HERE10 Aug 2012