How to Restore Master database

Before restoring master database, make sure

1. The build versions of the both instances (Current instance and the instance where backup is generated) should be the same.
• More Information at http://www.sanssql.com/2013/09/the-backup-of-system-database-on-device.html
2. The SQL Server instance is started in single user mode. Without this we will not be able to restore master database
• Add the "-m" parameter to SQL Server's startup parameter
  
• Restart the SQL Server Services
3. Restore the database
   

   RESTORE Database master
   FROM DISK ='C:\Backup\master.bak' -- Change Backup Location
   WITH REPLACE

After the master database is restored, the SQL Server instance will shut down automatically. Before you restart the server instance, remove the single-user startup parameter.
Once the SQL Server instances is restart, proceed with other recovery steps such as restoring any other missed databases or attaching missed databases, and correcting user mismatches and logins, etc...