How to display original control after clicking on dynamically added button

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C#

ASP.NET

I have a code in which- on clicking on "Comment" button creates a ("multiline textbox",and two buttons- "Submit" & "Cancel"). These controls are added to panel "PLComment". On clicking on Cancel button the panel should hide and "Comment" button should be displayed without page refresh. I have used AJAX also. Below is the code.
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ASPX:
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<div id="AnsCommentBox" class="question-answered question-answered-done">
                                        <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
                                        <asp:UpdatePanel ID="UpdatePanelComment" runat="server">
                                            <ContentTemplate>
                                                   <asp:Button ID="btnComment" runat="server" Text="Have a Comment?" CssClass="button btn btn-small" OnClick="PostComment" />
                                                <asp:Panel ID="PlComment" runat="server" ></asp:Panel>
                                            </ContentTemplate>
                                        </asp:UpdatePanel>
                                       <%-- <i class="icon-comments"></i>--%>
                                     
									</div>

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C# code:
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protected void PostComment(object sender,EventArgs e)
     {
         TextBox txtAnswerComment = new TextBox();
         Button btnSubmit = new Button();
         Button btnCancel = new Button();
         btnSubmit.Text = "Submit";
         btnCancel.Text = "Cancel";
         btnCancel.Style.Add("font-size", "12px;");
         btnCancel.Style.Add("Padding", "4px 10px;");
         btnCancel.Style.Add("font-size", "12px;");
         btnSubmit.Style.Add("Padding", "4px 10px;");

         btnSubmit.Attributes.Add("class", "button small blue-button");
         btnSubmit.Attributes.Add("runat", "server");
         btnSubmit.Style.Add("font-size", "12px");
         btnCancel.Attributes.Add("class", "button small red-button");
         btnCancel.Attributes.Add("runat", "server");

         txtAnswerComment.ID = "txtAnswerComment";
         txtAnswerComment.TextMode = TextBoxMode.MultiLine;
         txtAnswerComment.Style.Add("Width","700px;");
         txtAnswerComment.Style.Add("Height", "80px;");
         txtAnswerComment.Attributes.Add("runat", "server");
         txtAnswerComment.Font.Size = 9;
         txtAnswerComment.Style.Add("resize", "none;");
         PlComment.Controls.Add(txtAnswerComment);
         PlComment.Controls.Add(btnSubmit);
         PlComment.Controls.Add(btnCancel);
         btnComment.Visible = false;
        btnCancel.Click += btnCancel_Click;

     }

    protected void btnCancel_Click(object sender,EventArgs e)
        {
            
            PlComment.Visible = false;
            btnComment.Visible = true;
        }

What I have tried:

I have tried using AJAX but the "Comment" button shows after refreshing the page manually.