Thank you for letting us know about this issue that you have encountered. Apologies for whatever inconvenience this may have caused you.
Since your Master Password contains your private information, Trend Micro will not be able to retrieve your Master Password nor provide you a temporary password. You need to reset your account to create a new Master Password. For instructions on how to reset your Master Password, refer to this Knowledge Base article: Resetting the Master Password of Trend Micro Password Manager.
Note: Resetting your master password will also remove your saved passwords.