How to reset SAP* and DDIC user passwords

If you cannot log in as SAP*, you can carefully delete it at the database level.
Issue a delete statement against table USR02, which is the one that keeps the passwords.
Example: delete USR02 where BNAME = 'SAP*' and MANDT='100'
Make sure you delete it only in the desired client.
After this, you will be able to log on as SAP* again with password PASS.
Then, you can change the DDIC password and go from there.