Only the MDF file is left in a database. What should I do if I can't append the database?

Only the MDF file is left in a database. What should I do if I can't append the database?

1. Create a database with the same name
2. Modify Server Settings: allow direct modification to the directory of multiple systems
3. Stop SQL Server
4. overwrite the database file of the new database with the original MDF file
5. Restart SQL Server (in this case, the database should be in doubt)
6. Set the database to an emergency: Update master. DBO. sysdatabases set status = 32768 where name = dbname
7. Rebuild the log: DBCC rebulid_log ('dbname', 'logfile ')

Run the following statement to restart the database and restore the database.
Update master. DBO. sysdatabases set status = 16 Where name = dbname