If it was running fine and now it’s not, then something has changed, even if it wasn’t you that made the change.
Did you make any changes to the course content before the page stopped loading?
Are you the only “teacher” role in the affected course?
Does it affect only one course? or multiple courses? Or all courses?
Are you the only site admin?
Did you install/delete/upgrade any plugins prior to the change?
Can you log in and access other parts of your Moodle site?
What version and build number is your Moodle running? (Go to Site Admin > Notifications for this info)
What OS are you running on, and what are the versions of PHP, MySQL, etc (or their equivalents in your OS)? (Go to Site Admin > Server> PHP info for this info)
Are you shared, dedicated or internal hosting?
Has your hosting been upgraded?