Find the block diagram terminal for the object. If you have several terminals with the same data type, right-click the terminals and select Visible Items»Label from the shortcut menu. Find the object with the label that matches the hidden front panel object.
Right-click the terminal and select Show Control from the shortcut menu if the object is a control or Show Indicator if the object is an indicator.
You also can use the Visible property to display controls and indicators programmatically.