You might have faced a similar issue-once you change your Cpanel™ login details, and try to backup your SQL database from the "Backups" section, you are astounded to find out that the size of the database backup you just downloaded is just 20 bytes or so. If you believe that your database size is larger than that, then maybe the culprit is a file called my.cnf.
If you login to your server using FTP, and then click to go one level above the "public_html" directory, you will find that file there! This file is usually created as soon as you change your Cpanel login details (per my experience, this issue is not common to all Cpanel-based servers; it happens only on a few servers). You just need to logout of Cpanel, delete the "my.cnf" through FTP, then re-login into your Cpanel account and download the SQL backup again!
Did you notice any difference in the database size? :D
If the above fix does not work for you, my friend Rosie has other tips you may want to try! ;)
Please note that there is NO harm in deleting the “my.cnf” file from your server; however, if you want to, you may take a local backup of that file before deleting it.