Can't believe I can't find anyone else who has had this problem.
I'm using Overleaf for a project and at some point closed the file structure window to get more writing space. Well, now I can't find a way to get it back. I've tried refreshing, I've tried several different browsers, all to no avail. After researching, it seems people who have this problem with the preview bar have had success just clicking the area where the expansion should go, but that doesn't work for the file structure sidebar.
Here's a screenshot of what my workspace looks like: