Can't access Admin; Can't get rid of 'deprecated' messages

I dowloaded an older version of wordpress because I knew how to install it. Now, I cannot access the admin page or get rid of the deprecated messages. I have followed various suggestions that were given here. I have deleted the wp files and reloaded wp. I have deactivated the plugins. I don’t know how to reactivate them other than download yet another wp. I have added ‘error’ code to the php. I am at a loss as to what to do next. Please help. Thanks in advance for your assistance.