lost shortcut

I’ve suddenly lost the use of the shortcut (“Enter”) to play back in open GL mode. The “play” button works fine. Under preferences, the option to set any shortcut for “play” is missing. Same goes for the Flash or TB Studio shortcut menu options. I tried using a different keyboard, same result. The shortcut has not disappeared in any other program I use. Have I inadvertently changed a setting somewhere without realizing?
Ed ???

You actually want to look in the General category of shortcuts to find “Toggle Playback”. It’s set to Shift+Enter by default.