public void ReloadNote() 
        { 
            this.ButtonReload_Click(this,new EventArgs()); 
            NotesPanel.Update(); // panel inside user control is updating 
        } 
 

<asp:UpdatePanel ID="UpdatePanel1" runat="server"> 
   <ContentTemplate> 
     <asp:Button ID="btnReloadNoteTask" runat="server" style="visibility:hidden;" Text="Button" 
     OnClick="btnReloadNoteTask_Click" /> 
   </ContentTemplate> 
</asp:UpdatePanel> 

function ReloadTaskEvent() 
    { 
       __doPostBack('btnReloadNoteTask', ''); 

    } 

 protected void btnReloadNoteTask_Click(object sender, EventArgs e) 
        { 
         NoteControl.ReloadNote();    //first user control public method call 
         UpcomingHistoryControl.ReloadpcomingHistory();   //second user control public method call 
        }