Hello Murugesan,
Please review and ensure that the handlers are registered correctly and the necessary settings are added to the web.config:
Another thing you can try is using the CDN option to load the scripts and styles:
Also, you can try upgrading the project to the latest Telerik version and use the Lightweight Render Mode of the controls.
On the other hand, for such project specific issues please submit an official support ticket where we can discuss the exact scenario and provide suggestion more specific to your case:
Regards,
Peter Milchev
Progress Telerik