List view data not populate after search xamarin forms

After searching list data from search bar, list data not populate second time on list view after click on close icon from search bar?

here is my code for searching :

private void SearchAsset_TextChanged(object sender, TextChangedEventArgs e)
        {
            var keyword = SearchAsset.Text;
            WORRddlasset.ItemsSource = Assetddl.Where(name => name.Assettagnumber == keyword);
        }

 Assetddl = new ObservableCollection<Asset>();
                    foreach (var Asset in AssetData.Assets)
                    {

                        Assetddl.Add(new Asset { Assettagnumber = Asset.Assettagnumber, Name = Asset.Name });

                    }
                    Task.Run(() =>
                    {
                        Device.BeginInvokeOnMainThread(() =>
                        {

                            if (Assetddl.Count > 0)
                            {
                                WORRddlasset.ItemsSource = Assetddl;
                                loadAsset.IsVisible = false;
                                SearchAsset.IsVisible = true;
                            }
                            else
                            {
                                WORRddlasset.ItemsSource = null;
                                StatusLabel.Text = "No Asset Data Found!";
                            }
                        });
                    });

how to solve this?