[Rehan]

Depending on which version of MySQL is running on the server it might not even support the collate "utf8mb4_unicode_520_ci" and will show you this error.

Try to remove "COLLATE utf8mb4_unicode_520_ci" from the whole database backup (make sure you make a copy of it before removing anything or changing anything). After that try to import the database without this code.

Thanks @Hidden Refuge i have replaced those lines by " utf8mb4_general_ci ".It is working fine now.