Printer Icon Disappeared from Dock

Last night Apple did an update around 2 am. I happened to be up while it was going on, but not using my iMac. This morning when I signed in I noticed that in the dock where my canon printer icon should have been was a big white question mark. No evidence I have a printer connected. How do I remedy this and return the canon icon to the dock. Also, before the update I could actually see the picture images on my desktop, now i can only see that they are there but not the picture itself. I can live with that, but really preferred and found it easier to see the picture images. Thanks.