To unhide a hidden graphic, locate it at the bottom of the list (it will have an eyeball and a slash through it), select it, and select Unhide.
Repeat for each graphic that you wish to hide or unhide.
When done, select OK.
Note: This will need to be done in each ink selection in which you wish to hide the graphic: Colour (3 coloured circles), Black Only (Black 2 rectangle), or Blue Only (Blue 1 Rectangle).