GridView Paging in Asp.Net Custom Format

 I have a web  project in which I had to show  specific number of records and that that specific number of records  will display in each next and previous button . I have used List<> for the datasource  for GridView.

Source Code :-

<asp:GridView ID="GridViewItems" runat="server" Width="100%" DataKeyNames="Item_ID"

 OnPageIndexChanging="GridViewItems_PageIndexChanging"   PageSize="12" >

<asp:TemplateField>

                                    <FooterTemplate>

                                        <asp:Label ID="LblRecordCount" Text="" runat="server" Style="text-align: center;

                                            margin-left: -290px; font-size: 11px"></asp:Label>

                                        <asp:Button ID="BtnNext" runat="server" Text=">>" OnClick="BtnNext_Click" CssClass="ButtonPlain" />

                                        <asp:Button ID="BtnBack" runat="server" Text="<<" ToolTip="Previous" Style="margin-left: -117px"

                                            OnClick="BtnBack_Click" CssClass="ButtonPlain" />

                                    </FooterTemplate>

                                </asp:TemplateField>

C# Code :-

protected void Page_Load(object sender, EventArgs e)

        {

            try

            {

               

                if (IsPostBack == false)

                {

                    GetAllItem();

                    GetRecord();

                }

            }

            catch (Exception ex)

            {

            }

        }

    public void GetAllItem()

        {

            try

            {

                var ItemList = (from it in LstDetails()

                                orderby it.Item_ID descending

                                select it;

                if (ItemList.ToList().Count > 0)

                {

                    ViewState["RowCount"] = ItemList.ToList().Count;

                    GridViewItems.Visible = true;

                    GridViewItemVariation.Visible = false;

                    GridViewItems.DataSource = ItemList.ToList();

                    GridViewItems.DataBind();

                }

            }

            catch (Exception ex)

            {

            }

        }

      public void GetRecord()

        {

            int InitialCount = 1;

            int totalcount = int.Parse(ViewState["RowCount"].ToString());

            int num = GridViewItems.PageIndex + 1;

            int x = num * GridViewItems.PageSize;

            int z = x - GridViewItems.PageSize + 1;

            Button MyBtnBack = (Button)GridViewItems.FooterRow.FindControl("BtnBack");

            Button MyBtnNext = (Button)GridViewItems.FooterRow.FindControl("BtnNext");

            Label Mylabel = (Label)GridViewItems.FooterRow.FindControl("LblRecordCount");

            if (x > totalcount)

            {

                Mylabel.Text = z + " - " + totalcount + "  of " + totalcount;

                Mylabel.Visible = true;

            }

            else

            {

                Mylabel.Text = z + " - " + x + "  of " + totalcount;

                Mylabel.Visible = true;

            }

        }

 public void BtnNext_Click(object sender, EventArgs e)

        {

            if (Convert.ToString(ViewState["cc"]) == "")

            {

                GridViewItems.PageIndex = 1;

                ViewState["cc"] = GridViewItems.PageIndex;

            }

            else

            {

                if (GridViewItems.PageIndex < (int.Parse(ViewState["RowCount"].ToString()) / GridViewItems.PageSize))

                {

                    GridViewItems.PageIndex = int.Parse(ViewState["cc"].ToString()) + 1;

                    ViewState["cc"] = GridViewItems.PageIndex;

                }

            }

            GetAllItemCommon();

            GetRecord();

        }

        public void BtnBack_Click(object sender, EventArgs e)

        {

            if (Convert.ToString(ViewState["cc"]) != "")

            {

                if (GridViewItems.PageIndex > 0)

                {

                    GridViewItems.PageIndex = int.Parse(ViewState["cc"].ToString()) - 1;

                    ViewState["cc"] = GridViewItems.PageIndex;

                }

            }

            GetAllItemCommon();

            GetRecord();

        }