Hi Sam!
Can you share a screenshot of what you see when you try to join or host a meeting?
Are you on Windows, Mac, Android, iOS, Chromebook?
Basic Troubleshooting:
-Try restarting your computer.
-Sign out of your Zoom account on the Zoom App and test joining a meeting when you are signed out, and then sign in again and test if the issue persists.
-Completely uninstall the Zoom App and then download it again from Zoom.us/download
-Try on a different network (maybe you can tether to a Cellular Data connection) to troubleshoot if this is caused by internet connectivity or firewall issues.
Thanks,
Micah