Ah - then you have a problem - Gmail says that permanently deleted messages are "not recoverable in normal circumstances" - I think you'd need a Court Order.
Your only hope is if you have also accessed gmail using a third party program (like Outlook, Thunderbird or Apple Mail) at some point - then you may find some/all of the deleted messages are still available there.
I'm interested by your use of the word "Trash" - if you mean your computer (or tablet) Trash then that is not the same as Gmail's Bin - that is listed on the left hand menu of Gmail - below Inbox, Starred Important etc.
well I'm on Outlook and have just looked there - in my deleted - it says do you want to recover deleted - I said yes or ok and it brought me back to January 2018