I would recommend replacing the entire topcase. Here is a guide:
http://www.wonderhowto.com/how-to/v...p-case-and-keyboard-from-a-13-macbook-248940/
If you want to replace JUST the key's, then you will have to pry each key off one at a time, being careful to not break of the scissor spring things.
From here:
https://forums.macrumors.com/threads/226423/
To remove the keys:
For the BOTTOM ROW of keys (ctrl, space etc.) pull the key at the topside (nearest to screen) until it lets go with a 'click' (this can be a bit scary, with every key I feared I had broken the mechanism, but it actually turns out to be quite sturdy); then slide the key towards the topside.
The spacebar is a little bit more tricky, as it is attached at two points, and furthermore is connected to two little metal bars, but with appropriate pressure, these will also let go.
For the keys above the bottom row such as 'M' the procedure is basically the same, but you'll have to pull at the LEFT side, and then also slide the key to the left in order to remove it.
Please note that I did not take off any other key above the bottom row other than 'M'. I don't think it's likely, but it could be that the keys on the left side of the keyboard are connected differently: be careful.
To reassemble:
First slide the key from top to bottom (or left to right, for keys above the bottom row), then push down for the 'click' (spacebar should have two clicks for the mechanism, and several for the little metal bar)
Hopefully some pictures will clarify the process:
http://www.flickr.com/photos/meneert...7600841485908/
