under the column is a pop off button, you push a pencil or the likes up inside to free the key, that part is likely bad. you can roll up a business card or use a fat straw and cut it to length so it pushes the release button with the cap back on.

directions for opening the column are in this link http://sparkys-answers.com/2009/09/2...-changing.html iirc the part is in the pics there too.