Help with fixing blog post order

Hello! I cannot figure out how to fix my blog post order in WordPress. The issue: I had someone migrate my website from Squarespace to WordPress. When she set up the archive blog page, the posts all showed in chronological order, i.e. oldest first. I asked her to reverse it so the newest would show first, which she did with a plugin. I accidentally deleted that plugin. Then, I wanted to fix it and downloaded a different plugin which would allow to drag and drop the post order, but this didnt really work as posts weren’t showing up in the order I dragged them into. I have now deleted all plugins. The posts are showing up in correct order in my backend (newest first), but oldest first on the blog page. Can you help?

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