To recover your account, you post an address anywhere on the forum (where the conditions allow), prefereably in the corrosponding thread:
https://bitcointalk.org/index.php?topic=996318.0.
Someone will quote this. You then need to keep the private key of this address safe and secure so you can sign it if your account gets hacked.
There are multiple ways accounts can get hacked. They're normally due to people using weak guessable passwords. Requests to ther server are either done by picking security flaws in recaptcha that can be liberated or copying certain information from the servers.
If a dormant account is hacked or an account that cannot be recoeverd easily then the account could be used to scam (before it gets detected that it's been hacked). If you're ever unsure, the
seclog has all the recent password resets and account "wake ups".