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All Aluminium Macbook Pros (inc. unibody) have removable and replacable keyboards and trackpads. Many sellers on ebay sell both parts on there own; you don't have to replace the whole top case, trackpad and keyboard, if all you want/need to replace is the keyboard. Make sure you get the correct keyboard layout to match the top case, and vice versa.
There is a line printed on the keyboard connector ribbon; so long as that line is flush with the keyboard socket when the cable has been inserted and the socket latch is down, then you have connected the keyboard.
Two things to check - make sure the connector and socket are clean and no pins are damaged.
Keyboards can be purchased from powerbookmedic, thebookyard, ebay and aliexpress.