The inside of my post is wide, sidebar gone, and menu in list above the text

I have no idea what I did. I wrote a post and then everything was messed up but only when I open a post. My pages are fine. My site looks fine on a mobile device but on my laptop the post area is really wide, my design’s font is gone, the sidebar is gone, and my menu items are in a list above the post’s text.

I did embed a Twitter tweet in the post and that’s the only thing out of the ordinary that I’ve done but it was still messed up when I removed the embedded tweet. Any thoughts on how to fix it? Everything else in the post’s HTML looks normal.

Here is a post for an example: https://theantijunecleaver.com/2014/05/walk-on-air-in-the-reebok-skyscape/

This is a screenshot of what I see: https://i79.photobucket.com/albums/j159/fieryone1299/messeduppost_zps6562f73f.png

Thank you for your help. Please be aware that I am not a coding guru, I just know enough to get by ??