Use the tip of your screwdriver to pop the "Backspace " key off the keyboard (if it hasn't already fallen off). Turn the key upside down and use the tip of your screwdriver to pop the plastic frame out of the bottom of the key. Fit the plastic frame over the empty key space, making sure that the hooks on the laptop connect with the hinges on the frame. Fit the "Backspace " key back over the frame. Press gently down until the key snaps into place.