VBA Code To Hide Unhide A Number Of Rows

I am trying to create an input sheet with a specified number of rows. My plan was to hide all the empty rows in the table and ask how many rows were required in the table. A button would then be pressed to unhide all the relevant rows thus giving a table of the correct size. My best effort so far looks something like this:

Sub UnhideRows()
Dim i As Integer
Dim myRow As Integer
myRow = Range("A1") + 2
Application. ScreenUpdating = False
For i = Selection.Rows.Count To 1 Step -1
If WorksheetFunction. Sum(Selection.Rows(i)) > myRow Then
Selection.Rows(i).EntireRow.Hidden = True
End If
Next i
Application.ScreenUpdating = True
End Sub

the cell to give the size of the table is A1 and the table starts in A3. The first cell in each row has an index number (=row() - 2), all other cells would be empty to begin with. My attempt did not work.