Objects "disappear" when I deselect/add mesh

I was working through the “build a castle” tutorial, and I was having some trouble. I used extracation and resizing to build the tower, when I added a new mesh (a 5-vertix circle) my tower disappeared! I tried de-selecting the tower before adding the mesh, but my selection disappeared as if I had deleted it. I really don’t know what’s causing this, anyone have any ideas?

Check to see if you are in local view (View/Global view/Local view), or perhaps you are in a different layer and switched off the layer the castle is on (Click on the ~ key to show all layers)…

I checked and I was in global view. I also pressed the ~ key and nothing happened. I’m going to see if I there is an update and see if it works. Any other suggestions?