How can I assign commands to special keys (media button, eco mode button)
 

There is no way to do this with the keyboard settings... Some work becuse the voloume, mutue, next, and back buttons work (on the keyboard).

I have two non working keys (media player, and eco mode) is there some kind of file or command Ican gedit and assign a function to one of these keys?
(im new to this operation system,and dont know my way around it.) Linux mint 12 gnome 3

Ahh yes this must be a mystery

1. No need to repost. In fact, it's unhelpful to you because it takes your thread off the "zero replies" list, which many busy visitors routinely check.

2. In Gnome 2, if I press the Media button I get Gnome-mplayer. That's presumably because I've set that as the default using the System - Preferences - Preferred applications entry in the menu. If Gnome 3 lacks that, try right-clicking on a Nautilus entry for each type of media file, choose Properties, and set a default under Open with.

3. For the mysterious Eco, find its name by running xev and pressing it. Then run the Gnome configuration tool (you may need to install it) and somewhere in there will be a place where you can assign a name to a command (e.g. I have XF86Favourites attached to openoffice.org)

shhhhhweeeeeeeeeeet!

Suggestion:

Using X : xdev
xev | grep -A2 --line-buffered '^KeyRelease'

Using kernel : showkey
showkey

Sorry but that looks like alien speak to me...
Is that an example? What function does it assign to the key? I'm lost