The first thing you have to say is WHY? By starting a new account you will be abandoning your balances, your friends wont recognise you and you will leave behind all of your history of communications and games.
So what do you do if you lose your password?
On the NoPayPOKER login page you will see a link "New Password" click that link and follow the instructions to get a new temporary password. Once you receive that password you can login and change to a new, more memorable, password.
What do you do if you forgot your account username?
Contact support using the email address you registered with. Although NPP doesnt require that you fill in your contact details this is the point where it will really help as the support will ask you to verify some details on your account before they give you the username.
So now back to the original question....nope, never create a new account or you may be labelled a "multiaccounter" and your account(s) could be closed! Work with support to try and get back into your original account.