Supplier Registration Page

Hi Team,

We have made couple of changes lie renaming, making fields mandatory etc through sandbox, unfortunately at a stage unknowingly we have hided one of the mandatory fields and now sandbox is not allowing us to open the page itself when I am trying to unhide the field. Can someone help us out how to overcome this problem as we are in critical stage.

We hided the Tax Registration Type field, which is Mandatory above Supplier Type Field, now are trying to unhide that field the system is not letting us to unhide through sandbox. could you please help us to find a way to come out of this issue.