Since yesterday, when I connect to a server I have this error message
Also I lost all my identities and my servers synchronized (so i lost all my ranks on each servs)
I tried to disconnect / reconnect, I changed my password and I also tried to go to a public server like this one
but nothing has changed I still have the same problem.
What could I do to fix it?
What you describe is not a bug.
You can’t reach our services (check your client log) or you did reset your password and did not enter a recovery key.
You are logged in but the service for sync mytsid etc can not be reached or is not started.
I found my recovery key and now everything works!
Thank you for your answer!
This ticket can be closed
Edit after your post: Gratz 
We can not restore the key. You are the only person in the world who should have it.
Without the key you need to start from scratch via Fallback or Have a client where your data is still cached when you do a fallback on that Client.
