Don’t panic! While your password cannot be retrieved, it can easily be reset. Visit the login page and click I forgot my password. Follow the instructions and you should be able to log in again shortly. This process sends you a mail to the registered mail address for the user with a new password in addition to the username.
In the new password mail there is a link that you must click in order to make the new password active. See step 3 below.
The username associated with your mail address will be in the first section of the mail. If it was only your username you forgot - do not click the link to activate the new password.
Once you are logged back in, and you wish to change your password back to something more manageable than the system generated password - click here: ucp.php?i=ucp_profile&mode=reg_details
See below screenshots of the process.