If you have a backup introduced on the following page, please restore it
https://icts.nagoya-u.ac.jp/en/services/nuid/CAS/mfa_cas_seed_registration.html

If you have not made a backup, you will have to redo the settings.

Please follow the steps below to reset
https://icts.nagoya-u.ac.jp/en/services/nuid/CAS/#

Note that if you redo the settings, even if other devices and apps have valid CAS multi-factor authentication settings, they will be disabled and unusable.
Please refer to the following page for details
https://icts.nagoya-u.ac.jp/en/services/nuid/CAS/regist-multi.html