How Do I Unlock My IPhone 7 Plus With Activation Lock On It :ps i forgot my apple id i only remember it starting with an a but i remember my password

I Brought An Iphone From Boost it was $280 pre-owned nothing was wrong with it August 8th i was playing a game and i locked my phone i tried to unlock it i forgot my code to get into my phone so i kept trying to remember my passcode but i forgot it so i kept trying to put it in and it got it disabled then i went to apple so they can help me and it didnt work they connected it to a laptop and they restarted it now i have an activation lock on it please help me unlock it i dont want to buy another iphone its to much money