I accidentally deleted the all mailboxes in the sidebar of Mymail and I can't get it to come back. I use to be able to view all my emails in that one area and now I can't. How do I get that back?

I was in Mymail on my desktop and moved my mouse, heard a swoosh, and the section in my sidebar that listed all of my emails in one place at the top was gone. I have looked at all the menu options and can't find a way to get it back. I tried the edit, undo delete message, immediately after but it didn't work. How can I get all my emails to list under that one spot in my sidebar again? It was always at the top of the screen under the heading of Mailboxes with a subheading of Inbox and then it would list all the inboxes. Now I can only get to my inboxes if I go to each email individually and select the dropdown beside it where I can view the inbox and sent files and trash, etc. That setup is too cumbersome when I have 19 emails to monitor. Anybody know how to do this? I am working on a Mac mini M1, 2020 running macOS Monterey.