Help ! My server is invisible

Hello,
I tried to reinstall Plex Media Server from a backup. So I signed out from the server and from my account. I erased "Plex Media Server" directory from ~/Library/Application Support/ and "com.plexapp.plexmediaserver.plist" ~/Library/Preferences/. Then I put back "Plex Media Server" directory and "com.plexapp.plexmediaserver.plist" from a backup. I started Plex Media Server application.
After signing to my account on "http://127.0.0.1:32400/web/index.html" the Web App tells me that I don't have the authorization to access the server. Ok I'm not connected to it. But when I go to "settings" I don't see the server. And I cant't even create a new one if I wanted to.
What did I do wrong ?
Thank you for your answers.