Lost all my logins and Identity

Hi. I am new to this so please "bear with"

I downloaded windows 10 yesterday ( big mistake). which I now regret. To be able to download windows 10 I had to uninstall Norton. Again big mistake. After I realised that windows 10 for not for me I then uninstalled it. Back to windows 7 and Norton back on but somewhere along the way I have lost all my logins and Identity safe cards. I need them back as some of them I cant remember, Like my bank details for instance.  Please is there some way that I can retrieve them. Before you ask I did not back them up. Yes I know "Stupid" Someone please help me.