While trying to setup a key for the last keyboard macro in emacs (from Steve Yegge’s emacs page), somehow I got my f key bound to a game of 5×5 rather than binding my f5 key to the macro.
Makes things difficult. Rather than doing the easy thing by quitting and restarting, I made myself fix it. There’s a useful function called M-x describe-key which will give you the binding for a key. From that, I found that letters were bound to self-insert-command, and that the f was indeed bound to something else entirely.
So evaling this:
(global-set-key "f" 'self-insert-command) gave me back my f key. Of course, I had to copy and paste in the effs in that command.