useually you can pop keyboard keys out with a pair of pliers(ideal) or something lever like. try re-inserting the key, if theis works then thats ok.
If this does not work then the key is broken, you will need to buy another keyboard. or if you are a bleeding heart fixer-upper take another key that are not commonly used (like scroll lock or pause/break) winkle it out again and stuff it in the A space, then take a marker pen and write a capital A on it.
i would go for the latter, as it will give your keyboard more character!
Alex, August 2008