Initially, the best person to help you is yourself, cause:
First,
you'll need to see if your account still exist. You can do so by searching for your username on the
PlayerDex.
Then,
you'll need access to your email address (if you don't know which address you've used, you can use the
Recover My Account section to get your answer). I don't believe anything can be done if you don't.
After that, you'll have to go to
Recover My Account once again, fill in your details and ask for a Password Reset. If the mail doesn't appear in your Inbox, please be sure to
check your Spam/Junk folder as well, since they sometimes might end up there.
Though mails shouldn't take that long to arrive, in some cases
it can take up to an hour or so.
If you haven't gotten a message by then,
add noreply@pokemon-world-online.com to your 'Safe senders and domains' list, and try again.
And in case you don't get a response the second time around either:
go to the #Support channel in the Discord server and describe that you've done all the above, cause certain email providers might block the password reset mail because they've worded it weirdly.