Multiple Things Not Working even after REINSTALL

I just finished a clean reinstall of WordPress (keeping only wp-config.php & wp-content), but I’ve still lost functionality of multiple things in the administration.
Everything was working fine, but over the weekend I installed a few plugins (can list later when I get home) and when I went to post today I noticed the problems. Before reinstalling, I did disable all plug-ins, but that didn’t seem to affect anything.

1. I cannot access the visual editor mode. It’s stuck in HTML. I’ve tried a variety of the methods here in the forums to correct this problem and none have worked.

2. I later discovered that I cannot create new categories and many buttons are not working.

Let me know what I can post here than might help to solve the problem.
Thanks in advance!