I was being stupid and decided to take off the shift key and just pop it back on, and now it won't go back on. I've tried everything. It's not lost or anything, just won't click into place. Please help!
Wide keys like shift usually have a wire bar of sorts on the underside, so be sure to set that in the right place before trying to snap it back down. On the Apple aluminum keyboards, the bar should be first snapped to the top end of the key (on the underside), then passed through the two metal loops towards the outside of the key recess before the key is pressed into place.