You can make AceText visible again with a single left-click on AceText’s icon next to the system clock. If you right-click the icon you’ll get a popup menu with a “Restore AceText” item at the top. This item is bold to remind you that it’s the default action when you left-click the icon. You can click the menu item to restore AceText too.
If you prefer to use the keyboard, you can configure a hotkey to make AceText appear. The Restore AceText item at the top of the right-click menu of AceText’s tray icon reminds you of the present hotkey, if one is enabled.