First, check your spam or junk mail folders. There is a chance that the email with the ticket was automatically filtered out by your email service.
If the ticket is not there, there may have been a misspelling of the email address when you booked. If this is the case, you can identify the ticket seller from your bank statement. Usually, the name of the company that received the payment is listed next to the amount deducted. Contact the seller to see if the email address is spelled correctly and if so, ask to have the document re-sent.
We are working on adding the ability to automatically track the name of online travel agencies to our app. This should help in cases like this or other unintentional errors.
You can always contact us at email@example.com, so we can help you find the seller.