haven’t used the player for a while. Fired it up today and my media isn’t there. Get a message saying add your media by downloading the media server - which is already running!
It sounds like your server is no longer claimed by your Plex account for some reason. You want to check your server:s dashboard (by browsing to the actual local IP address for it).
If you’re still needing help, please give information on your setup. Starting with what OS your server is running on.