Oh sorry to hear that. You must backup the file before updating if you have customized the code. So we always recommended to create a child theme so that while updating to new version your customized code will not be lost. There is no any way to revert you content.
Yes you can once contact to your hosting provider. They must have backup of it of early date. So ask them to revert your theme before last backup taken. If there is no backup on hosting provider then you again need to made code customization.