Repair WordPress installation?

I’m having some really funk problems with my wordpress site.

This is an odd problem to be having across the board, but basically anytime I’m in my dashboard and trying to expand a block (for example, Appearance–>Widgets–>Default Sidebar–>Text), I click on the arrow but nothing happens.

Another problem is that even though my pages have content (i.e. https://www.yarniapdx.com), when I go into edit mode, all that displays is a blank screen.

Essentially, I have no ability to make any changes via my dashboard or back end at all.

I have tried reinstalling the newest version of WordPress, and have updated my theme and all plugins (and in fact disabled all plugins too), but nothing seems to help.

Is it possible that my core WordPress files somehow got corrupted? If so, is there a way to delete and reinstall my WordPress installation without messing up any of my content? Would that even help?