Function doajaxPost(){
    var returned_value="";

    // #############I NEED THIS CODE TO TRY TO POST THE DATA TO THE SERVER AND KEEP
    // #############TRYING FOR 10 SECONDS AND THEN CONTINUE WITH THE REST OF THE CODE.
        jQuery.ajax({
            url: 'ajaxhandler.php',
            success: function (result) {
                returned_value=result;
            },
            async: false
        });
    // ###################################################

    alert(returned_value);

    some other code
    .
    .
    .
 }

jQuery.ajax({
    url: 'ajaxhandler.php',
    success: function (result) {
        returned_value=result;
    },
    timeout: 10000,
    async: false
});

$.ajax({
   url: "ajaxhandler.php",
   ...
   timeout: 10000,
   ...
});