There is no way to recover a master password. For security reasons.
However, you can reset the master password. After resetting, you will be able to unlock the locked sticky notes. But you will not see the required content in it. Because the old master password was used to encrypt it.
You can reset the master password from the below Preferences option. To access Notezilla 's Preferences, right click on Notezilla icon in windows system tray and choose Preferences from the menu.