How to Change Your Steam Passwordby Seth Amery ; Updated September 22, 2017
Changing your password periodically is a good habit to maintain, especially to protect financial information stored online with a web-based service like Steam. You can change your password at any time, but you will need access to your email account for the fastest results.
Resetting a Password Via Steam Client
Load the Steam client and click "Retrieve a Lost Account" when the login box appears. Selecting "I know my account name" and "Next" brings you to the next page, where you can type in your account name and wait for an email from Steam. In that email, there is a code you must enter into the client; you must also answer your security question, included in the email. If the code and answer are correct, you can enter your new password right away.
Resetting a Password Without an Account Name
If you don't remember the username you used to log into your Steam account, you can still get a code emailed to you. In the Steam client, selecting "I don't know my account name" gives you the option to pick "I remember the contact email address I used." Enter the email attached to your Steam account, where you'll receive your username; you can use this information to locate your password using the previous method.
Resetting a Password Without Email Access
If you don't have access to your email account or remember the old email you used, the best you can do is obtain a product key registered to your account; unless the key was saved somewhere, such as in a Steamworks physical retail game, there won't be any way to find it. If you can retrieve your account name using a product code, you can email Steam Support with the product key and your account name to seek further help.
Resetting the Secret Question on Steam
When you regain access to your Steam account, be sure to update the security question as well. If your password had been compromised, there's no reason to think your security question wasn't; leaving it as-is creates a back door into your Steam account. Open the Steam client Settings menu and select "Change password or my secret question" to reset your security question.