So I was also in the boat of I reset my password, and signed out everywhere, which kicked my Plex Docker server (binhex-plex) offline, and I could not claim it through the Plex settings like others had.
So what I did was:
ssh into my unraid server
get a claim code from https://www.plex.tv/claim/
run this command with that claim code:
curl -X POST 'http://127.0.0.1:32400/myplex/claim?token=claim-xxxxxxx'
After a few seconds, some XML was printed into my terminal (which you can ignore), and when I went back to https://app.plex.tv , my Plex server showed up again! All content was accessible again.
Thanks to this comment for the tips