I'm not sure if this is an Inspiron, but on the basis that laptop keyboards are similar in design, perhaps the photos in the link below will help you;
http://www.laptoprepair101.com/laptop/2007/03/20/key-fell-off-keyboard/comment-page-2/
Scroll down to where he clips the spacebar back in.
Mark
OK, this might sound a bit silly but i've managed to break the spacebar on my DELL Inspiron 1420 laptop keyboard. I spilt some food on the keyboard and was cleaning it and removed the spacebar but for the life of me I can't get it back on. I still have all the pieces (the metal bar, and both parts of both key hinges) but for the life of me can't get it to reattach like I was able with other keys. Usually when reattaching another key I would just press down and it would click in place but cant seem to get this one to latch on and stay. ANy ideas on what I should do to get it back on? I would hate to get a new keyboard just because of this and that I still have all the parts.

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