I had this problem the other day. The up arrow key popped off. First I turned off the computer. No, correct that, first I cussed since my Dell is only a few weeks old. Anyway, if you look at it, the plastic thingies on the bottom are hinged and kind of drop down. The key hooks in three places-one on the top of the pad and one on each side. First I attached the one on the top and then pushed down and the sides hooked themselves. Maybe I just got lucky, but it worked for me. Good luck.
Sue S, January 2006