How's it going.Let me read of your question. Give me a minute.
Sorry I had to go but I am back now and ready to have a look when you are.
Hi There. I am Bing. It seems your case is urgent so I look forward to helping you with your issue today.
Basically you want to get access to a lost Gmail account which was used by you for a long while. Is it correct?
Did you use it to send out emails to some contacts of you?
Was that email address ever associated with other Google services such as Google Voice?
Okay, it seems you have to go here to retrieve your username.
I've forgotten my Google Account username
Sorry to know that. Did you have your phone number associated with the Gmail address?
If probably, try inputing your phone number from here. You may also check this Youtube video to see if it could help. Good luck!
mmm... I did receive an automatic call to my land number for recovering password, but I forgot it was for Google or eBay or PayPal... :(
Wish you good luck anyway. :)
Per Google, the options for you are here.
Choose "I forgot my password" then choose "No" for "Do you use Gmail with this account", then follow the screen instructions to do the remaining options.
The very last resort is to let Google know the phone number you provided was a land number, let them to handle this manually, if luckily.
Also if it were me, I would try more to guess the email address, per my way (my personal naming convention, my unique event related to that email address or the date when the email address was created etc).
BTW, did you enable Find My Mac on the stolen Mac? If yes, go to iCould.com to lock your Mac.
Is your Apple ID the same Gmail address? If yes, call Apple to check the email address per your Mac's serial number (if it was directly purchased from Apple, they should have the record).
Regarding how to contact Google, try if you can get to this page if you always say no and change different challenge questions.
Sorry I can't simply give you my link, as it is specific for my address.
Need to leave for a while. Good luck!