You don't need to remember your old one. Or you can open the game and click on Reset Password below the sign-in. A new one will be sent to the e-mail address that is associated with your account. By default, that'll be the e-mail address making up your user name.
Guild Wars 2: Issue after Issue (Very Angry) Sooo, I went to try to reset my password for my old GW1 account and the password reset side of the site wasn't working, so I sent a support ticket with a newly made account and they sent me an email a day after, telling me they've made a link so I can reset it and after recovering my old GW1 accountSORRY I know its the wrong forum, but this is the one with the most coverage, thought I should ask in here to get a quick answer before it got removed. So basically, I tried to reset my password but it requires me to input code that got sent into my phone number, which, after 20 tries and long waIf your Guild Wars account is linked to an ArenaNet account, you can also provide details about your Guild Wars 2 account, such as: Your First and Last Name; Your Billing Address; Any Guild Wars 2 Serial Code(s) used on the account; The Date of Birth listed on the account; The SMS Authentication Number used for the account