If you know your Steam Account name:

1. Select the I know my account name. option and click Next.
2. Enter your account name in the Account name field and click Next.
3. Check the contact email address for your Steam account for an email containing your Verification Code and Secret Question. If you didn't receive this email message, Contact Steam Support.
4. Enter your verification code and the answer to your secret question in the Verification code and Secret answer fields respectively, then click Next.
5. Steam will next require you to select a new password. Enter your new password twice to confirm the change, then click the Next button to reset your password.

Please observe the following process to update your password or secret question after logging in to your Steam account: