$('img').click(function () {
    $("#shikh_sec").attr("disabled", true); // doesn't work :/
    }
so , how to fix this and disable that element when clicking on the "img" tag
$('img').click(function () {
    $("#shikh_sec").attr("disabled", true); // doesn't work :/
    }
so , how to fix this and disable that element when clicking on the "img" tag
 
    
    Assuming #shikh_sec is an input that can be disabled (there's no such thing as a disabled p element, etc.), you want prop():
$('#shikh_sec').prop('disabled', true);
 
    
    The code is missing a trailing ");"
A correct version would be something like this
$('#disable-me').click(function () {
$(this).attr("disabled", true); // doesn't work :/
});
JSFiddle: http://jsfiddle.net/5v4mysgt/
 
    
    Try using disabled instead of true:
$('img').click(function () {
    $("#shikh_sec").attr("disabled", "disabled");
}
$(function(){
  $('img').click(function () {
    $("#shikh_sec").attr("disabled", "disabled");
  });
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<img src="http://ichef.bbci.co.uk/news/ws/200/amz/worldservice/live/assets/images/2014/09/23/140923115528_ultima_hora_640x360_bbc_nocredit.jpg">
    
<input id="shikh_sec" type="button" value="OK"> 
    
    Or just with a pure javascript:
$('img').click(function () {
    document.getElementById("shikh_sec").disabled = true;
});