Yesterday, I tried to use the equation editor on Moodle while adding a quiz question. It caused Firefox to crash. Since then my moodle account is not working correctly on any browser. I've uninstalled and reinstalled firefox. I've also restarted my computer several times. I cannot click on the arrows to open up menus. And the editing tools are not showing up when I try to add a question or do anything else for that matter.
Have you tried accessing your Moodle from another computer? This might allow you to confirm that it is something with Moodle and not with your computer.
Are you making backups of your Moodle?
Have you tried rebooting your Moodle server? I would also try removing the equation editor plugin, see if Moodle comes back, and then reinstall.