I saved my .ai as .pdf in order to send a proof to client. I then made another days worth of changes and hit "Save" and then "close". Now I've realised that because I most recently saved as PDF, that was the file I then saved over. My major issue now is that all the important content is sitting off the artboard, but because I've saved as PDF - I cannot access it. I can see the data displaying within the PDF in the preview thumbnail of the document (In Illustrator's recent file list) but when I open it, it asks me to specify an artboard and only opens the artboard content. Is there anyway that I can get to the "off-artboard" content?
Based on feedback through various forums and the response from Adobe tech support staff - it appears the answer is: the content is lost and cannot be accessed.
I will ensure that I never "File / Save as / PDF (proof quality/no editing capabilities" again as it opens me up to potentially making changes and unwittingly saving them without being able to access them again. Instead I will know always "file / Save a copy..." to ensure the file that remains open after save is my 'raw' AI file.