After loading ArchiCAD 10 to my Mac, I was working on two files in ArchiCAD 9. When I tried to open with version 9 them several days later, the program froze up. When trying to open them with ArchiCAD 10, the file opens with no model information. I can merge the files into a new ArchiCAD 10 file, whereupon all information appears. However, when these new files are saved, the files open with no model information when trying to reopen them. The only hint I have of what may be going wrong is that the zoom field at the bottom bar of the drawing says "nan %".
Plan or 3D window? You are zoomed too far away.
Try zooming to fit; if anything is very far from the rest of the project, that will not help.
Chek the 3D, axo view, with all the layers on and unlocked. If you see nothing, activate the arrow tool, Select All. Some black dots should appear - if you see one bunch at one side, and another on another side, that's it.
Otherwise, just merge the file into your template, and resave ...
ArchiCAD since 4.55 ... 1995