Your question is not so clear.. but make sure about below things..
1) Make sure you have included
jquery.js
2) Check the import order of
jquery.js
and
lightbox
JS in
head
tag
3) Make sure you write all your code inside
$(document).ready()
as shown below
4) Make sure you use proper selectors..
$(document).ready(function()
{
});
Hope this will be helpful..