Compare the key to the base of the keyboard where you plan to reattach it to make sure that this latch is present. If it isn't, then you may need a replacement key.
[header] How to reattach a keyboard key [title] Inspect the back of the key for damage. [step] Turn the key over to make sure that the part of the key that latches onto the keyboard is still in place. You should see a small plastic piece that will attach back onto the keyboard base.