If you wish to transfer your current account's data, at the signup page x10Premium click the "Transfer existing x10Hosting Account" button and enter your account username. However, it looks like your previous x10Hosting account was terminated, so this transfer option isn't possible unless you have created a new one.
I have opened an inquiry with the administrative staff to determine if backups are even available at this point as the account was already terminated; there is no guarantee that there are however, as on free hosting backups are normally the sole responsibility of the customer to keep. Once I know more information I will update here.
I've confirmed with the administrative staff that no backup is available for the account; unfortunately we won't be able to process a migration to premium due to this, although you would still be able to start fresh with a new account if you so choose. In the future, I would strongly recommend keeping your own backups of the files/databases present (while Premium does keep backups on its own, no service is 100% failure-proof, so it's strongly recommended that you keep your own backups as well).