A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hi, I understand how important that spreadsheet is to you and how disruptive this issue can be. What’s happening is likely tied to Windows updates forcing Excel to close in the background while the file is still open, which can cause incomplete saves or corruption, especially with older file formats or password-protected workbooks. To help prevent this, try closing Excel before updates run, convert the file to the modern .xlsx format for better stability, and consider enabling AutoSave or storing it in OneDrive so version history is available. It’s also a good idea to keep a backup copy in a separate folder. Can you confirm if the file is still in the old .xls format and whether AutoSave is turned on? That will help us figure out the best next step.Regards,
Aron