SQL Server – Make Database Inaccessible Through ‘sa’ User

You should never do this using detach. Until we know more about exactly what state your database is in now, for next time, you should do the following:

1. ALTER DATABASE SET OFFLINE
2. For each file, ALTER DATABASE MODIFY FILE
3. copy the files to the new location
4. ALTER DATABASE SET ONLINE
5. when everything is working, delete the original files

The reason you don't want to do this with detach, and the reason you want to copy the files instead of moving them, is because when something goes wrong in either of those processes, you have exactly 0 copies of your database. Or the situation you're in now.

Not sure how dbo is coming into play. Here is how you create a user in a database mapped to a server login, whether that login is already associated to a user in any other database:

CREATE LOGIN foo WITH PASSWORD = 'bar', CHECK_POLICY = OFF;
GO
CREATE DATABASE splunge;
GO
USE splunge;
GO
CREATE USER foo FROM LOGIN [foo];
GO
-- then permissions:
GRANT ... TO foo;
EXEC sp_addrolemember N'<role>', N'foo';
etc.