Unfortunatley this complicates things.....it doesn't really make sense. Products are automatically saved when you bring them in via the spreadsheet interface. When you close autocad and the spreadsheet closes with it, all spreadsheet changes are remembered.
In your case there is a step involved that we arent seeing that made your products disappear, or some strange glitch. I think the first thing to do, is see if you can reproduce the same results. Open autocad, go to the spreadsheet interface, drop a couple cabinets in (do not save), and then shut down autocad. Re open autocad, go back to the spreadsheet again, see if your products are there. If they are not, you need to call tech support immediatley. If they are, then that means there had to have been something else that happened that only you could remember. (I know this isn't comforting, but it's the only thing I can think of that adds up). Regardless, you need to be able to use the software and rely on the fact that your products will be saved. Actually for your security, you should probably contact tech support any way. Toll Free: (800) 204-0913