Using the Zudoku Program Using the Zudoku ProgramUse Menu/File/Save to save your current puzzle, including your solution so far. You might do this to continue it later. Saving is also useful if you have reached a critical step where you need to guess a number to see where it leads, but may need to backtrack to try a different guess. You will provide a file name for the saved puzzle.
If you want to save a copy of the start data only so you can start from the beginning some other time (or share it with a friend), then select Menu/File/Restart to clear your solution but keep start data, then Menu/File/Save to save the puzzle at its start.
Select Menu/File/Open to open one of your saved files. You will be in Solving Mode when the puzzle is loaded. Any work you did when you saved it will still be there.
You can also simply double click on any .SUD file with Windows Explorer to bring up Zudoku with that data file loaded.