How it works
The Unhide All function will allow you to unhide your workbook’s hidden rows, columns, and sheets.
How to use it:

Step 1
In the ‘More’ drop down of the Formatting and Grooming group, click on ‘Unhide All’.
A new pop-up window will appear.

Step 2
Select if you want to unhide everything in the current workbook or all workbooks.
Yes = Everything & No = Current Only
On selection, the function will run.