If the future, you will want to save a backup on your PC, and at least one other copy to a thumb drive, SD chip to the cloud or somewhere else then the PC you did the draft on. You do this by using "Save As" and giving the location of the external place you want to save. But then that drive becomes your default save location. You don't want that. So then re-save to your PC, by executing Save As a second time to write over the original file on your PC. Then when you Save it will write over the file on your PC.
For your missing file that you spent 12 hours on. Try searching for it with your file app in the /documents/turbotax directory. put *.tax2016 in the search box. I hope you find it. If you do then do save it somewhere else as I advised above. Personally I save it to an SD card in my camera. Good to encrypt it if that place you saved your backup is not secure. Your personal info is on that file. Good Luck!
