If you've forgotten your password on Resonite, it's easy to reset it. Just follow the steps right here on this page.
Requesting a password recovery code
Launch Resonite from Steam, ensuring that you're logged out of any user accounts.
In the top left, click "Login/Register":
In the pop-up click "Lost Password"
Enter the primary email of the account you want to reset a password on, into the email field and then press "Send Recovery Code".
Using a password recovery code
Check your emails for an email from Resonite. It should look like this:
In the email, there's a recovery code. Copy this into the recovery code field on Resonite and then enter your new password into both of the additional fields on the form.
Click "Set New Password"
Then you're done, you should be able to use your new password.