Get text/value from textbox after value/text changed server side

I have a FormView with data(DataSource,DataBind) that I fill with value='<%# Eval("Name") %>' , but after I'm changing the text in TextBox and press update button I see the same value that before, I cant see new value that I have typed.

What I am missing here?

my html

<asp:FormView ID="MainFormTemplate" runat="server">  
    <ItemTemplate>
        <li class="li_result" runat="server">
            <div class="col-3">
                <input id="txt_Name"   runat="server"   value='<%# Eval("Name") %>'>
            </div>
        </li>
    </ItemTemplate>
</asp:FormView>
<asp:Button id="btn_Update" runat="server" OnClick="btn_Update_Click" Text="Update" />

Server side

protected void Page_Load(object sender, EventArgs e)
{
    using (DB_MikaDataContext data = new DB_MikaDataContext())
    { 
        MainFormTemplate.DataSource = data.File_Projects.Where(x => x.Num_Tik.Equals("12")).ToList();
        MainFormTemplate.DataBind();             
    }        
}


public void btn_Update_Click(object sender, EventArgs e)
{      
    //using System.Web.UI.HtmlControls
    HtmlInputText twt = (HtmlInputText)MainFormTemplate.FindControl("txt_Name");
    string text = twt.Value;//i see old value ,not new one that i typed in text box    
}

In every postback, you are always getting the old value from your database. The solution is check if the page is being rendered for the first time (!IsPostBack) then set your MainFormTemplate's DataSource else if is being loaded in response to a postback (IsPostBack) get the txt_Name's value like this:

HtmlInputText twt;

protected void Page_Load(object sender, EventArgs e)
{
      if (!IsPostBack)
      {
           using (DB_MikaDataContext data = new DB_MikaDataContext())
           { 
                MainFormTemplate.DataSource = data.File_Projects.Where(x => x.Num_Tik.Equals("12")).ToList();
                MainFormTemplate.DataBind();
           }
      }
      else 
      {
           twt = MainFormTemplate.FindControl("txt_Name") as HtmlInputText;
      }           
}

protected void btn_Update_OnClick(object sender, EventArgs e)
{
     string text = twt.Value; // You will get the new value
}

with Page_Load executing every postback, you are always writing value from database (?), and value sent from browser is lost (although still exist in Page.Request.Form member).

In ASP.NET, When a page is submitted, the Page_Load event runs before the button click event. So, the textbox value gets repopulated with its original value before the click event looks at that value.

If this is the situation, then you can wrap the code that assigns the value to the textbox in an if block like this:

if (!IsPostBack)
{
    HtmlInputText twt = (HtmlInputText)MainFormTemplate.FindControl("txt_Name");
    string text = twt.Value;
}

Hope this helps you.