To unhide all rows and columns...
Code:
Columns.EntireColumn.Hidden = False
Rows.EntireRow.Hidden = False
I don't recommend hidden row/column detection on workbook open. As far as I know you'd need to loop through range column by column and row by row to detect.
Something like below to check for hidden row and/or columns.
Code:
Dim i As Long, x As Long
x = 0
With Worksheets(1).Cells(3, 1).CurrentRegion
For i = 1 To .Rows.Count
If .Rows(i).Hidden = True Then
x = i
End If
Next
For i = 1 To .Columns.Count
If .Columns(i).Hidden = True Then
x = i
End If
Next
If x >= 1 Then
MsgBox "There is hidden row and/or column"
End If
End With
For filter it depends on what you want to check for. Do you want presence of Filter checked or only when Filter is applied and rows hidden?