Auto Hide and Unhide Rows Based

Hi, I am on this project which needs a VB code which automatically hide or unhide rows based from a value on a certain cell. I have to admit that I am not that proficient in VB Codes and Macro and any help would be highly appreciated. I have tried the following code below:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Range("C12").Value = CVErr(xlErrNum) Then
Rows("1:13").EntireRow.Hidden = True
Else
Rows("1:13").EntireRow.Hidden = False
End If
End Sub


Unfortunately, I am only successful in hiding the rows and not in unhiding it after I input data on another sheet (TallySheet). I attached a file of my project, and the worksheet I am working on is named Summary. Hoping for your help guys. Thanks in advance.