So I have 2 accounts, one Gmail which is level 7 and is intact after update. other one is a Trainer Club account which is level 22 and it got completely reset after update to a level new account, had to choose Pokemon and nickname all over again. I have tried everything I could find on internet in past 2 days but nothing worked so far. I spent so much time and money on this account that I won't be able to start all over again.
I'd suggest opening a ticket with pokemon trainer club, not niantic. Apparently the PTC login goes to a different Nintendo/Pokemon Company server before going to niantic, as thousands of PTC-login players were locked out during server maintenance on launch week, while Google-login players were far better off, and many managed to play just fine.
TL;DR, see if Nintendo can help you out. Since these accounts can have money poured into them, there's probably a legal failsafe to prevent a server hiccup or an accidental deletion from completely destroying all account data.