Do you know how your site was hacked. There are many ways to hack a site. (sql injection, code injection, password hacked giving access to parts of your server.

You need to find out exactly how your server was compromised. Do you have access to your server log files. If so you need to take a look at the log files around the day you were hacked. Once you know who and how you were hacked, I can suggest was to prevent further hacks of this type. As you are on a shared hosting service, and not a VPS see more or dedicated server, you will need the help of your hosting provider.