I've had the same problem sometimes where my events will randomly pop up on my screen. You should be able to just drag it back into your "widget" menu. Open your menu by pressing the black arrow tab on the left side of your screen. Then drag the "no event" back into your menu and it should shrink down to an icon-looking thing. Then you can press the arrow tab again to minimize the menu. You can customize your widget in the settings so that events aren't in the menu anymore.

My phone has this little message in the middle of the screen that says "No event" & I can't get it to go away. Is this a problem? Does anyone know how I can get it to go away?