I checked the default directory- documents/juice calculator- but it is empty. Would the file be somewhere else?
The file could be somewhere else. When you save your first file the program will launch the Windows file browser and position you in the default directory (documents/juicecalculator) but you have the option to navigate to another directory and save.
After you save the file, the calculator will remember the last file that you saved and always open that file when it is launched.
If you do a File->Close the opened juice file will be closed and you will be presented with an empty juice file allowing you to build new recipes/ingredients and until you do a File->Save As, the Save buttons will be greyed out.
The difficulty that I believe you may be in is that your juice file is saved in a directory somewhere but the you don't know the location of where it was saved. Here is a couple of things to try:
1. Did you have the "backup" options turned on (Tools->Backup Options)? If so, the file can be located in the "Backup location".
2. You can also look in your "My Documents" folder and see if the
filename.xml is located there since that is a Windows default save location.
3. If you are running Windows 7 or Windows 8 (I don't remember if this was in earlier versions of Windows) and launch Windows explorer and go to "My Documents". In the upper right corner of the window you will see a "Search Documents" box. Type in "*.xml" and see if it locates your named juice file.
4. By chance, is your computer setup with multiple users and did you use another username to logon to Windows to build your juice file. If you did, the file might be stored in the other users "My Documents" location.