This did not work for me.

"Steve" wrote:

Click the blank box to the left of the column headers and above row 1 to
select the entire worksheet.
Then do Format Columns Unhide.

"Bank Boy" wrote:

In working with a spreadsheet, I hid some of the columns that I was not
using, so that I could work with it better. I hid Column A and now I cannot
unhide it. I can't highlight the columns before and after to unhide, because
there is nothing before Column A.