A key fell of my laptop keyboard?

the seven key fell off my keyboard, it isnt entirely nescessary but i do want it back on. Where the key used to be is a black rubber thing that is what was pressed to make the key respond. There are 2 metal things at the top of the hole, and one larger metal thing at the bottom. These three metal things look like they fit with the bottom of my key cap. On the bottom of the cap is a black plastic contraption. It has a circle in the middle and a few sockest for the metal to go. I tried pressing it onto the socket and tried to line it up but i cant do it without seieng. I need to get the lack thing off the key cap so i can put that on alone then put the key cap on top of it once its connected? how do i do this?