I have another Stack Exchange account, which I had been using for years from my mobile phone, but my mobile phone got lost, and I cannot remember the email associated with my account, I only know the username. How can I retrieve my email (the email associated with the user name of the old account) so that I may merge my old stack exchange account with the new one I accidentally created when trying to reset my password?
If you know the username I think it should be straightforward for you to get a link to that profile and then use the Contact button to contact and describe your situation to SE staff.
The I accidentally created two accounts; how do I merge them? instructions in the Help of every site may also be useful to you.