Sub LockRows()

Dim wks As Worksheet
Dim LastRow As Long
Dim rw As Long

For Each wks In Worksheets
With wks
.Unprotect Password:="MyPass"
.Cells.Locked = False
LastRow = .Cells(Rows.Count, "A").End(xlUp).Row

For rw = 2 To LastRow
If Trim(.Cells(rw, "A").value) < "" Then
.Rows(rw).Locked = True
End If
Next rw
.Protect "MyPass", DrawingObjects:=False, Contents:=True,
Scenarios:= _
True, AllowFormattingCells:=True, AllowFormattingColumns:=True, _
AllowFormattingRows:=True, AllowInsertingColumns:=True, _
AllowInsertingRows :=True, AllowDeletingColumns:=True, _
AllowDeletingRows:=True, AllowSorting _
:=True, AllowFiltering:=True
'.Protect Password:="MyPass"
End With
Next wks
End Sub