Strange thing happened this weekend. Typically in Maya I'm able to create a primitive poly object. I can create it, go over to the attribute editor and/or channel box and be able to change the density of the primitive's polygons. For some reason I can't do that anymore. The option just disappeared. So now I'm stuck with the default poly count for these primitives, which doesn't work for me.
Is this a plug-in issue? Is there a checkbox somewhere that I might have accidentally unchecked?
Yes, it sounds like you accidentally unchecked your Construction History. There's a button in the status line that looks like a little scroll (it will look different depending on your version of Maya).