Can not log a return for an online order

I ordered 2 pairs of shoes for my toddler and need to return one. When attempting to log in to my account it said it doesn’t exist or was blocked so I had to create a new one, but even though I used the same email address it doesn’t pick up the order. I’ve tried to send multiple emails which all get a “could not be delivered” response, and have had no response to multiple online contact form submissions.