I noticed that in a worksheet that I have been keeping for years, many of the dates in one column, entered as, e.g., 4/15/01, now show as a five-digit number, such as 40987. Interestingly, this has not happened on another, similar sheet in the same workbook.

Checking the cell formatting, the problem cells appear to have been formatted as a non-asterisked date format of the type indicated above, so, as I understand it, they shouldn't be influenced by other changes. I found one that had an asterisked date format and changed it to non-asterisked, but nothing happened.

I was guessing that perhaps daylight savings time on the computer might have caused a problem, but I don't recall this happening in the past, and anyway the date format has no time in it.

Can I restore these? They are purchase dates for various items and while it's possible I have them in a saved backup, I don't know how long the problem has existed.