Twitter requires users to create unique usernames to protect the security of their accounts. If you forget your username, you will be unable to log in to your account. Your Internet browser has probably saved your username somewhere on your computer, but if all else fails, Twitter provides a means of retrieving your username and password.
Modern Internet browsers offer users the option of saving information that is commonly entered into certain fields, such as an email address to register for a newsletter or Twitter. The browser also saves username and password information, which can keep a user permanently logged in to a page. If you have recently deleted your cookies or other Internet history, this information will not automatically log you in, but it may still be stored within the browser. Access the browser's "Preferences" menu and locate the "Saved Passwords menu" (usually found within a Security tab) to browse a list of all usernames and passwords saved to the browser.
Many Twitter users send most of their tweets with a cellphone, either through text messages sent to the service or by way of a smart phone app designed for Twitter. If you have a Twitter app buried on your phone somewhere that you forgot about, check the app. It's likely that if you were ever logged in, you are still logged in and can see your username.
Log in with Email Address
Twitter allows users to log in with either their username or a registered email address. Visit the Twitter homepage and click the "Sign In" button. Log in with the email account with which you registered your Twitter account. You will still need your password to log in successfully.
Send Username to Email
If you have forgotten your Twitter username and your password, the website still provides you with a means of recovering both. Visit the Twitter homepage and click the "Sign In" button. Click the "Forgot username?" link and enter the email address you used to register your Twitter account. Your username and password information will be sent to you in an email instantly.