Forgetting email usernames and passwords is a very common occurrence for us. Given our multiple email accounts and other websites that require registration, we are forever searching through our records for the right combination.
So instead of spending time searching through piles of sticky notes and documents we just found an easier solution.
Download LastPass an application that works as a password manager. Anytime you log onto a website that requires a password the application will give you the option to add it to the Lastpass database.
The laptop application is free but for the mobile version you can have access to it for an affordable $12 a year.