Hi,
This is likely because an Admin in your system has changed your UI configuration (Layout Template) to hide this option. Or a change to your access level restricting access to Financial Information has happened.
If you are not an Admin, I'd recommend reaching out to your system administrator. If you are an admin yourself, I would check what layout template is applied to your user profile and ensure that Billing records are set to be visible.
Best Regards,
Rich.