Gmail emails recovery

hi,
one of my friend knew the password of my email account. we have some important chats in it. then after we have some problems between us. and i forgot to change my password. she deleted all the mails and chats from inbox, chat list, all mails and trashes too. and its really very important for me to get them back otherwise it could create a huge problem for me and for my career. please help me out and suggest something.