RESTORE DATABASE master FROM WITH REPLACE

To restore a full database backup of master, use the following RESTORE DATABASE Transact-SQL statement: Step 3: Restore master database with database backup Step 2: Open but not login SQL Server 2012 Management with Administrator, and click 'New Query'.

More detailed information, please refer to: How to Set SQL Server Access with Single User Mode Now SQL Server would start in single user mode. In MSSQLSERVER Properties window, stop this service. Open Control Panel – System and Security – Administrative Tools – Services – MSSQLSERVER. Step 1: Start the server instance in single-user mode. The following passage would intend to talk about how to restore a master database with database backup in single user mode. Therefore, SQL Server cannot start if master database is unavailable.

And master database is the database that records the existence of other databases and the location of those database files records the initialization information for SQL Server. This includes instance-wide metadata such as logon accounts, endpoints, linked servers, and system configuration settings. Master database records all the system-level information about SQL Server system. How can SQL Server 2012 restore database, especially master database, the most important SQL Server database? SQL Server couldn't start because of master database unavailable. How to Restore an Unavailable Master Database in SQL Server 2012

Sql repair master database