I’m sorry you’re experiencing problems.
I see you noted having already tried some troubleshooting steps (thanks!) – just for the avoidance of doubt though can you confirm you tried them in the following order or would it be possible to do so now?
- Please ensure The Events Calendar and Events Calendar PRO are up-to-date
- Deactivate all other plugins
- Now switch to a default and completely unmodified theme (such as Twenty Thirteen)
- Visit the Permalink Settings page (though you need change nothing – just visiting it should trigger a refresh of WordPress’s rewrite rules)
- Now check again
Can you reach the affected events now?