My harddisk has bitlocker and I know the password but not the recovery key.
I didn't save the recovery key because I know the password.
My computer was clean and has a new windows 7. I don't know if is because of that!
Can anyone answer me?
If you installed a new Windows setup over the old one, your user account and their passwords are gone, you need the recovery keys. You save the recovery keys IN CASE you forget the password or have some other issue where you can't normally get to the files. Just like any other backup, you need to do the saving BEFORE you have an issue, not try to fix it after the fact.
Your encryped files are gone, be careful using encryption next time. Read the warning and instructions fully.