For anyone who has come through the discord channel with Mac issues, and who might come in the future, your computer OS version, plus when you were able to play and when it stopped working are important. Some of the steps change in terms of how to fix the issue. Some people will need to have a CoH app in applications. Most don't.
The best steps are to fresh install as manga said, then restart your computer. If you need troubleshooting help, I'm sure either me, or someone will be around on discord to help you out.
By the way, manga, thank you very much for island rum and giving us a way to play CoH again and thank you for all the time and effort you've put into solving as many issues as you could.