1. You need to check if the script you use for your web site is up to date. You must update it to latest version. You need to contact your software vendor or web developer regarding steps how you can do the update.
2. You should scan your account for any files uploaded by the attacker under your public_html folder. They may upload php shells to be able to edit your files even after you update your software. Any files not uploaded by you must be removed from public_html.
3. You must change the permssions of your configuration files which contain passwords to 600. Each script has such a file which contains the login details for MySQL. It needs to be chmod to 600 so that others can’t read it and steal the password.
4. You must change your password for cPanel to a hard to guess password. A hard to guess password is 7Bzh@!z;lP!@%Zdf.
5. Change the MySQL password to a new one which is hard to guess and then update it in the configuration file of your script. For WordPress the configuration file is called wp-config.php. The MySQL password can be changed from cPanel -> MySQL databases.
6. You should scan your computer for viruses in case your password was stolen by a trojan on your computer.
If your web site files were injected with malware, you should follow the steps above and also remove the malware code from your files. The malware is a virus which usually resides within iframe html code. You need to check your files and remove the malware from the infected ones.
There is nothing else you need to do regarding this. If your account gets compromised again after you have updated your software, that means you missed to update/secure some script which was used to hack your account. You will need to recheck everything from scratch and see if you missed to update any modules/extensions you installed in your account. It is very important to keep your account up to date and secure.