Firstly, check your email spam folder in case it was sent there (if you can also mark it as not being spam that would be really helpful)

If it isn't there, log in with the email address and password you used when you purchased tickets

Then head to the 'My bookings' tab of the Dashboard. There, you'll find all the details of all bookings you made with that account

You can also download your tickets from there and request a refund if necessary