<Grid x:Name="Grid1" Loaded="Grid_Loaded_1">
        <DataGrid x:Name="datagrid1" ItemsSource="{Binding}"/>
</Grid>

    public partial class MainWindow : Window
    {
        //public ObservableCollection<customers> customerses = new ObservableCollection<customers>();
        //public ObservableCollection<customers> customerses = new ObservableCollection<customers>(from z in   MyAppDataContext.customers orderby z.id select z);
        public BindingList<customers> customerses;
        private DataClasses1DataContext MyAppDataContext = new DataClasses1DataContext();
         

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Grid_Loaded_1(object sender, RoutedEventArgs e)
        {
            // customerses = (from z in MyAppDataContext.customers orderby z.id select z) as ObservableCollection<customers>;
            //customerses = (from z in MyAppDataContext.customers orderby z.id select z).ToList<customers> as ObservableCollection;
            //customerses = (from z in MyAppDataContext.customers orderby z.id select z) as ObservableCollection<customers>;

            customerses = ((from z in MyAppDataContext.customers orderby z.id select z) as IListSource).GetList() as BindingList<customers>;
            
            Grid1.DataContext = customerses;
        }
    }

namespace WpfApplication21
{
    /// <summary>
    /// Логика взаимодействия для MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public DataClasses1DataContext DC = new DataClasses1DataContext();
        private ObservableCollection<customers> customersObserv;
       

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded_1(object sender, RoutedEventArgs e)
        {

            customersObserv = new ObservableCollection<customers>(from z in DC.customers select z);

            System.Windows.Data.CollectionViewSource customersViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("customersViewSource")));
            // Загрузите данные, установив свойство CollectionViewSource.Source:
            // customersViewSource.Source = [универсальный источник данных]
            customersViewSource.Source = customersObserv;
        }
    }
}

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:WpfApplication21" mc:Ignorable="d" x:Class="WpfApplication21.MainWindow"
        Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded_1">
    <Window.Resources>
        <CollectionViewSource x:Key="customersViewSource" d:DesignSource="{d:DesignInstance {x:Type local:customers}, CreateList=True}"/>
    </Window.Resources>
    <Grid DataContext="{StaticResource customersViewSource}">
        <DataGrid x:Name="customersDataGrid" AutoGenerateColumns="False" EnableRowVirtualization="True" ItemsSource="{Binding}" RowDetailsVisibilityMode="VisibleWhenSelected">
            <DataGrid.Columns>
                <DataGridTextColumn x:Name="actual_addressColumn" Binding="{Binding actual_address}" Header="actual address" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="commentsColumn" Binding="{Binding comments}" Header="comments" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="fullNameColumn" Binding="{Binding FullName}" Header="Full Name" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="idColumn" Binding="{Binding id}" Header="id" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="iNNColumn" Binding="{Binding INN}" Header="INN" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="nameColumn" Binding="{Binding Name}" Header="Name" Width="SizeToHeader"/>
                <DataGridTextColumn x:Name="registered_addressColumn" Binding="{Binding registered_address}" Header="registered address" Width="SizeToHeader"/>
            </DataGrid.Columns>
        </DataGrid>

    </Grid>
</Window>