Do you use secret questions to secure your account in addition to a strong password and secure email?
If yes, then find the solution here. But I'm a little surprised why the thread or solution from the user I quoted never got any merit when it was really helpful. I agree it is an old thread and easier to ignore. I gave him 1.
This is a Public Service Announcement:
If you lose your password,
DO NOT USE THE SECRET QUESTION TO RECOVER THE ACCOUNT. It will result in your account being locked. Please use the email recovery option to recover the account.
The reason that the accounts are locked is because the May 2015 hack leaked Bitcointalk's database which did not securely secure the Secret Question and Answer. To prevent people from guessing the answers, theymos made it so that accounts that are recovered using the secret question are automatically locked when the option is attempted. This is to prevent hackers who may be able to guess the answers from the leaked database.
If you have had your account locked, to recover it, please send and email to the email displayed on your screen when you try to login. You can also create a new account and pm both theymos and badbear. In the email and PM, to prove your identity,
You MUST sign a message with a bitcoin address that you have posted previously, at least 2 months prior. Please be patient. Theymos and BadBear are busy people. Your email or pm may become lost among all of the other stuff that they have to do. You should resent your email and pm once a week so that they will see it and get around to you. If you need help signing a message, check this thread:
https://bitcointalksearch.org/topic/how-to-sign-a-message-990345If you haven't lost your password yet or you have regained access to the account, don't set the secret question, it can be a hassle.
Make sure that you have the email set to an email address that you can access. That will make everything so much easier and will not require the long recovery process.
Another possibility is that your email has been compromised by hackers and the hacker has locked your account via an email link. I've read that an account buyer can no longer access his account after 6 hours of changing his email and password because the owner or seller locked it via an email link some time ago. If you are not the primary owner of that account then a signed message is mandatory to prove it. Hopefully you will get access to the account again soon.