New Outlook

I was satisfied with the way Outlook used to run with the delete button at the top of the page and subfolders where you could move things. For some reason the internet updated and now I'm using this new Outlook Web App. I think it is ridiculous and want to go back to the way it used to be. My boss still has the "old" version that I started with when my account was first created. Does anyone know what I'm talking about and more importantly how to go back to the other (better)version of Outlook that is not a web app? Any help is greatly appreciated because I lost some important documents when the switch occured and cannot access them with this new system.  Thank you.