An event receipt or confirmation can be resent from the user front-end (as an event registrant) or the dashboard (as an admin).
As an event registrant
Navigate to the event page.
Click on View Receipt.
Enter the email where they'd like to send the receipt. (This can be their own or something else.)
Click on Send.
You may share this document with community members with instructions on how to resend their receipt.
As an admin
Sign in to the dashboard.
Click on Events on the menu on the left.
Select the relevant event from the list.
Click on Attendees and select the relevant attendee from the list.
Click on Resend Receipt.
This will send the receipt to the email address for that attendee, where it may be forwarded further.