It is better to fix your old listings than create new ones. If you create new ones, you will lose all your reviews and sales on the old ones. Sales are a big factor in your ranking, so you don't want to lose those. You can simply move the old listing to a different section if you need to, then edit whatever you need to.
Sometimes sections disappear, but if you refresh the page, they then come back. Or try another web browser. Are you on Desktop or Mobile? Sometimes they work on one and not the other. Also be sure you are in Active listings and not Featured or another category like Sold Listings or Inactive listings if you don't have any listings in those.
I think that "ugly" page you are referring to is the new listing form. There is a box at the top of the page where you can change it back to the old listing form if you preferred the old one.
You do your editing under the tab that says "Listings."
