If you have forgotten your email account's password or other settings, you can easily reset the password by logging into your cPanel account (Example: http://www.yourdomain.com/cpanel) and clicking on the 'Email Accounts' link under 'MAIL'. Then find the email account in question there and click on "Reset Password", located further down the row. You should always choose a password that is secure, and then make note of that password somewhere safe. We like KeyPass, which is a free software package that keeps your passwords all in one spot on your computer and is password protected.
If you need help setting up your email accounts in the email client you're using (ie: Outlook, Outlook Express, Thunderbird, etc.), you can also click on the "More" dropdown and then on "Configure Email Client". Once there, you can choose to automatically configure or make note of the Manual Settings.