|re: "when I reopened it the auto sum is not working"|
I'm not sure what you mean by "auto sum".
In Excel, AutoSum is represented as the Greek Capital letter Sigma Σ in the toolbar. When you select a cell and click the AutoSum symbol, it looks for numbers above the cell (or to the left if there are no numbers above it) and SUMs them.
While you've done a fine job of describing how you use your spreadsheet, keep in mind that we can't see it from where we're sitting.
Perhaps it would help if you included the formula that you are using (the one that is not working) and the basic lay-out of the spreadsheet. i.e. what's in the cells that the formula references, etc.