Do you have have any Apple devices, like iPhone, iPod or iPad ? If Yes, then you can find the Apple ID there (It'd be your email address). On that device, go to Settings > iTunes & App Store and you will find it there.
Your Apple ID is the email address that you have registered with Apple. If you don't remember it, then you can find your Apple ID from here --- > https://iforgot.apple.com/appleid
Once you get the Apple ID, reset the password ***** Apple ID from here if you don't remember the password ***** > https://iforgot.apple.com/
If you have any difficulty on finding the Apple ID or if you don't have one, then you can create one from here --> https://appleid.apple.com/account
If you have any questions or would like any additional information, please don't hesitate to ask.