Plenty Of Fish accounts are deleted for numorus reasons.Please be sure to thoroughly read through the sites TOS ( Terms Of Service ) to be sure you did not break any rules.
If you have forgotten the username associated with profile you can type in the email address used to sign up.
Pay attention to those pof login names that catch your curiosity.
Remember, this is a dating site that allows you to view profiles without signing up in any manor.
One of these upgrades is the capability to change your username or login.
Unless you decide to upgrade your account, you will never have the ability to edit your POF Login name. Why not search other profiles to see what others are doing.