|re: "I can not click on that column at all"|
Do you mean that you can not select that column?
Unless your mouse is broken, I'm pretty sure that you can click on the column. Nothing may happen, but you can still click on it.
How do you know that the sheet is not protected?
I ask because a sheet can be protected in such a manner that only specific ranges are locked and protected from selection while allowing the rest of the sheet to be free to use.
Select any cell and click on Format...Cells. Does the Protection tab appear in the dialog box?
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