Messed up theme with upgrade

This is an older site I set up with Marketpress. I went in and ran an update to get them to the latest version, and it screwed up the way the store looks. Most of the pages are ok enough that I can fix them, but the single product pages are really wonky, and I can’t figure out what template they are using, and why they are not using the same template as the rest of the store.

It’s been so long since I set this site up and customized it, that I am not 100% sure what I did. The product page does not appear to be using my single.php, which it basically should be. Whatever template it is using has the correct sidebar in it, but nor wrapped in a div that makes it a … sidebar. :wink:

Since it seems a lot has changed since I set it up, I don’t know where to look to get back what I had before. I do have a backup, but nothing is leaping out at me.