after deleting my facebook account, the federated authentication stopped working so I tried to log in using the gmail address I had registered against my Facebook account. I had to reset the password and after logging on, I was presented with the correct user name (real name) but no playlists and a basic account. The app on my mobile phone was still authenticated so I extracted the username (random lettes/numbers) and tried to log on using that. Again I had to reset the password and logging on I found my premium account incl. playlists and history (relief), however, the user name is a hash. Interestingly, the confirmations for both password resets were sent to the same email address, so it looks like there are two accounts linked to one emai? Is there a way to consolidate these so I can get my real name back as user name?
Since the link between your Facebook and Spotify accounts was broken, some parts of the information used to create your Spotify account were disconnected, like the name you have on your Facebook profile (that's why you're seeing a hash username instead). In order to access that account, you need to password and you'll be good to go.
However, since you're mentioning that your email address is also linked to another Spotify account, our best recommendation would be to close it with the steps you'll find here (be careful not to close your Facebook-created one!).
Once you've done that, your email address will only be associated with the account you regularly use, and you'll be able to set the password from this link.
Lastly, although it's not possible to change Spotify usernames, you can find some useful tips and suggestions here.