Ah jesus, at least I've deleted that "profile" file, I've restarted my system and it works! With the lastest version.
The program started and I've connected using automatic function. The starting window said "password ok" but it didn't close! So I closed it manually (pff!) At the beggining there was only the inbox folder and the Trash so I was terrified. But I was lucky because after sending the first email the "Sent" folders appeared.
Now please also check this screenshot:
In version 11 of Thunderbird I had everything in one category. Inbox, Outbox, Sent and Trash. Now why does Thunderbird seperate all these stuff in 2 different categories?
And how can I merge them? In which category and how? Because that thing is frustrating.
ps. I hope many others will find this post useful. After Firefox, Mozilla prooves that is uncapable of doing a serious job! If Google makes a Thunderbird clone (stand-alone, not in-browser) it will lead, like it already does with Chrome! It's just a matter of time!