I have used "readonly" attribute to the textbox which makes the textbox non editable and may i know how to disable the readonly attribute on clicking the button. c
Well, to be simple! You can use jQuery to remove this attribute (jQuery would be simple, you can do this using JS too). Here is the code for that:
$('input[type=submit]').click(function () { $('input[type=text]').removeAttr('readonly'); })
https://api.jquery.com/removeAttr/