BEING FORGETFUL LUCY IS NOT AN EXCUSE

I have been an xbox fanatic. I have bought several xbox unit and I already have it’s latest version. I also have been playing xbox live with my friends. We spend time together playing through network connection. Just last week, I had this crazy day. i forgot my email address for xbox live. I don’t know how I have forgotten it, but I really did forget it! I guess I changed my email address during the time when I was very sleepy and didn’t quite know what I was doing. So now, I’m stuck here retrieving my email address. My buddies are now waiting for me to go live on xbox but I can’t. I still have to know my email. How do I retrieve it?can I still retrieve it?or should I go back to scratch?