If you are using v5.56 or earlier: You can reset your password through the Recovery Center if you are a registered user. (But only folders protected by the "Normal" security level can be restored. We cannot decrypt folders protected by the "High" or "Highest" security level.) Learn more about Recovery Center
If the folder is protected by version 5.70 or higher and a recovery email has been set, you may retrieve the password through the "Recovery Mailbox" function. Learn more about password retrieval