Only you can recover your ”server accounts” (tied to TS Identities), but only if:
a) an Identity you used to enter this server has been synced on myTeamSpeak, you are logged in to the same myTS account and haven’t tried to reset password while being logged off;
b) you have a local copy of that Identity;
c) you have your Recovery Key in case you had reset your password.
In option A, just simply log in to the same myTS Account you were using when joining that specific server and your ranks and everything should be fine.
In option B, you’ll need to import that Identity and connect to server using it. That’s all.
In option C, after you log in, there should come out an error that myTS cannot decrypt your data. In this case, paste your Recovery Key (which you should have saved in safe place, as mentioned by TS Client) and accept what’s next. Your data will be decrypted and you should get new Recovery Key after that.
If you had no myTS Account, haven’t synced any Identities, haven’t saved them locally and/or haven’t saved your Recovery Key you’re screwed, cause
no one beside you, even TS Devs/Admins/Staff cannot help you!
This is a great lesson for you for the future.