Private Sub Worksheet_Change(ByVal Target As Range)
Const strPassword As String = "Password" 'Change this as necessary
'This macro assumes you will want to allow users to edit the 3 columns if the cell doesn't
'contain either of the two specified values (If not remove code specified below)
'A Worksheet will start out with Locked highlighted for everycell
'This needs to be removed first Manually - Select all cells, Properties, Uncheck Locked
'Check which cell has been changed (the one containing the value which will lock/unlock columns
If Target.Address = "$A$1" Then
    'If Cell = Value to Lock 3 Columns
    If Target.Value = "Value to Lock 3 Columns" Then 'Change as Necessary
        'Unprotect Worksheet
        ActiveSheet.Unprotect Password:=strPassword
        'UnLock 3 Columns then relock
        Range("B:D").Locked = False
        Range("B:D").Locked = True
        'Protect Worksheet
        ActiveSheet.Protect Password:=strPassword
    'Otherwise if cell = Value to Lock 2 Columns
    ElseIf Target.Value = "Value to Lock 2 Columns" Then 'Change as necessary
        'Unprotect Worksheet
        ActiveSheet.Unprotect Password:=strPassword
        'UnLock 2 Columns then relock
        Range("B:D").Locked = False
        Range("B:C").Locked = True
        'Protect Worksheet
        ActiveSheet.Protect Password:=strPassword
    'Otherwise if Cell = Anything Else
    Else
        'Unprotect Worksheet                            'Remove if required
        ActiveSheet.Unprotect Password:=strPassword     'Remove if required
        'UnLock 3 Columns                               'Remove if required
        Range("B:D").Locked = False                     'Remove if required
        'Protect Worksheet                              'Remove if required
        ActiveSheet.Protect Password:=strPassword       'Remove if required
    End If
Else
End If
End Sub