@kartik786 you seem to have found a solution. Could you share with us? I am having similar issues with PDF’s hosted on the same server as the WordPress site, even though the absolute URL link is perfect.
External files work just fine, but this isn’t an option for me as the files need to exist on the same server.
@dazziola I haven’t figured it out actually. It seemed there was outage of google DNS in India due to a flood in Chennai. Once that was solved, the viewer started re-appearing.
What’s your web url? Let me take a look and see if I can solve it.
@dazziola .. did you try checking if the permissions on the folder where these files are hosted is correct? Check folder and file permissions once just to be sure.