I have password protected an Excel spreadsheet and a copy named 'ONE' is saved to my documents. The only way to open this sheet is now with a password and I thought it was safe!
I prepared another spreadsheet named 'TWO', which was not protected and saved this to my documents as well.
Both names are fictitious BUT, by mistake, after editing spreadsheet 'TWO' I saved it as 'ONE'. It completely overwrote the contents of 'ONE' without asking for a password and the original contents were lost!!
How can I prevent this sort of thing happening again?
Protecting workbooks or worksheets has no effect on whether you can overwrite or simply delete files. Protection is simply to protect the structure (workbook) or content (worksheet). It is also notoriously insecure.