If you don’t see a Calendar event or are having trouble finding it, there are several things to check.
Make sure the calendar that contains the event has a checkmark by its name.
Make sure your calendar account is still set up. For example, if you turn off the iCloud Calendar feature in iCloud preferences or Internet Accounts preferences (or sign out of iCloud in iCloud preferences), you won’t see your iCloud calendars in Calendar. For more information, see Change iCloud feature settings.
Scroll your calendar to see more dates and times.
If your declined events disappear from Calendar, and you want to see them again, choose View > Show Declined Events.
Search for events in the Calendar search field.
If you don’t see your all-day events, make sure Show All-Day Events has a checkmark beside it in the View menu.
If you changed the time zone for an event or changed the Calendar time zone, make sure you’re looking for the event at the correct time. Calendar adjusts where the event appears based on the time zone.
Make sure your computer’s date, time, and time zone are set correctly in Date & Time preferences.