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.