Hi Praveep,
Please check:
https://www.maxmegamenu.com/documentation/removing-residual-styling/
I suspect if you replace:
<div id=”navbar” class=”collapse navbar-collapse navbar-ex1-collapse”>
With:
<div>
.. it will solve a lot of problems, as your theme will no longer be able to apply it’s own CSS and functionality to the menu.
Please also check your page for JavaScript errors, as these will make the menu fall back to using CSS only, and you will only get limited functionality:
https://www.maxmegamenu.com/documentation/javascript-errors-console/
If you are still stuck, please summarise the issue and post a link to your site (this is very important as every site is different, so I need to see the code to work out what the problem is).
Regards,
Tom