Web Method not getting called

it seems that you are attempting to call a WebMethod named getPopUp from your AddRecommendedBooks.aspx page using AJAX. However, there are a few points to consider:

1. WebMethod Accessibility: Ensure that the getPopUp method is declared as public static in your code-behind file (code-behind for AddRecommendedBooks.aspx).

2. ScriptManager: If you are using an ASP.NET Web Forms application, make sure you have a ScriptManager control on your page. The ScriptManager enables the page to handle AJAX requests.

3. PageMethods: If you're not using a ScriptManager, you can try using the PageMethods object to call the WebMethod. Modify your AJAX call as follows:

4. $.ajax({
       type: "POST",
       url: "AddRecommendedBooks.aspx/getPopUp",
       contentType: "application/json; charset=utf-8",
       dataType: "json",
       success: function (response) {
           // Handle the response if needed
           console.log("C# code executed successfully.");
       },
       error: function (xhr, textStatus, errorThrown) {
           // Handle the error if needed
           console.log("Error executing C# code:", errorThrown);
       }
   });
   

   Replace the above AJAX call with the following code:

5. PageMethods.getPopUp(onSuccess, onError);
   
   function onSuccess(response) {
       // Handle the response if needed
       console.log("C# code executed successfully.");
   }
   
   function onError(xhr, textStatus, errorThrown) {
       // Handle the error if needed
       console.log("Error executing C# code:", errorThrown);
   }
   

   Ensure that the EnablePageMethods attribute is set to true in your ScriptManager or in the page directive (EnablePageMethods="true").

   Additionally, make sure your web application is running on a server that supports ASP.NET AJAX, as the WebMethod call won't work with static HTML files.

Make sure that the AddRecommendedBooks.aspx page has the ScriptManager control added to it. The ScriptManager control is required for enabling ASP.NET AJAX functionality.