You can restore a hacked or damaged website from a backup file. How you complete the restore depends on how you created the backup:

From your client area go to:

Services -> My Services -> click on the green "Active" button -> Login to cPanel/Control Panel

In the account Dashboard, click cPanel Admin.

In the cPanel Home page, in the Files section, click Backup.

In the Restore a Home Directory Backup area, click Browse and then select the backup file (file name ends in tar.gz) on your local computer. Click Upload.

cPanel begins the restore, and when complete you'll see a (long) list of all the files that were restored.