if you have a "Fn" key for dual use keys (think numpad mixed into "qwerty" portion), you may have muted it
i turned off a wireless radio that way once.. i hate laptop keyboards, lol. shift keys around, change their shapes etc... type 1/2 speed due differences on some occasions. turn off wireless, mute sound, <enter> instead of "" etc... (slash / in quotes doesn't show up)