If you are having an issue with Excel’s unhide rows not working, you may discover that it is because the rows are not actually hidden.
The most common cause for this is frozen panes but you can see the other reasons that unhide rows is not working here.
For people who are not familiar with frozen panes, Excel gives you the ability to freeze some rows so that you always see them no matter how far down you scroll (watch a video clip on multiple windows to see how).
Occasionally it may look like rows have been hidden but instead the rows have been frozen, but not from row 1. So when you look at the spreadsheet it looks like the first row is say row 60 and the assumption is that the other rows are hidden. However it is because the rows were frozen from row 60.
To see the other rows you need to unfreeze the panes (click on the ribbon under VIEW, FREEZE PANES then UNFREEZE PANES). This will give you access to the other rows.