Or you could make a macro and insert it in a module. Here is the macro which
will unhide all hidden rows and columns:
Sub ShowAllHiddenRowsAndColumns()
Dim ColumnsHidden As Range, RowsHidden As Range
For Each ColumnsHidden In ActiveSheet.UsedRange.Columns
If ColumnsHidden.Hidden Then
ColumnsHidden.Hidden = False
End If
Next
For Each RowsHidden In ActiveSheet.UsedRange.Rows
If RowsHidden.Hidden Then
RowsHidden.Hidden = False
End If
Next
End Sub

Swisse