How to get Alt-F2 back?

My system crashed a few days ago. One thing that is not working anymore is that I can't hit Alt-F2 to open up a pop up window that allows me to type in a command (such as kwrite) which starts kwrite immediately, instead of my having to go to the kmenu, or starting a bash shell (the pop up disappears as soon as the command is run).

What can I do to get this key sequence to work again (Alt-F2), and is there a post, or a site, that describes other shortcuts? I'm aware of the KDE control center that shows some shortcuts, I'm wondering about other shortcuts that I know exist, but don't know what they are.

Also, is there a site that describes what the key sequences are for the SysRq key, and how to use the key after a crash?

How about the other keys (windows, sleep, wake up, power) and remapping them? Is there a site that explains this? Can someone post a how to <a href=http://www.knoppix.net/forum/viewtopic.php?t=2398&sid=2cab65d4f996b37e28b0f97a8 6956c01>here</a>?
http://www.knoppix.net/forum/viewtop...b0f97a86956c01

Thanks!