Help please z8

i have forgotten my email and security i made this account a long time ago, i remmember the password and username cuz i saved them on my computer i need to have the password changed, i think sum1 got ahold of my account when my other computer was crashed, luckily i had everything on my usb memory sadly i never thought id need my email or sec (which was stupid) because i knew i wouldnt forget my login since it was saved. PLEASE HELP ME SUM1 HAS ALREADY SOLD A DEAGLE FROM MY ACCOUNT!!! i dont want my stuff back i just need my pass changed so that i dont freaking lose everything.