If a coworker shared their calendar with you, but you lost the invitation, you can add their calendar to your Outlook as follows:

1. Open Outlook
2. Go to Calendar
3. On the left pane, right-click on My Calendars or Shared Calendars (your preference)
4. Go to Add Calendar > Open Shared Calendar
5. Type the complete email address of your coworker in the text box
6. Click OK

That’s it.  You should now see your coworker’s shared calendar.  Depending on the privileges assigned to you, you may:

• View their busy vs. available times
• View the details of their appointments
• View, edit, and add appointments