If your website is broken after installation of Premium URL Shortener, it is most likely because you installed the script on the non-ssl version of your domain i.e. http://domain.com and your server is enforcing SSL and redirecting all requests from http to https.
In this case, you will need to go to your phpmyadmin (or equivalent database manager), then go to the database you installed the script on, find the settings table and search for the row where config is equal to url. After you find it, edit that row and replace the http part of your domain by https. This should fix the issue permanently.