SQL Server is a relational model database server developed by Microsoft. When users create databases, SQL Server gives them the option of creating backups. These backups are stored in BAK format and can be used to restore database contents if the original files are deleted or corrupted. Opening BAK files and restoring a SQL Server database is a simple process involving the SQL Server Management Studio application.
Click the Windows Start button, then select the following: "Programs" > "Microsoft SQL Server" > "SQL Server Management Studio." Log in to the server using the administrator username and password.
Right-click the database icon on the left-hand side of the SQL Server Management Studio screen. Select "Restore Database." Locate the field labeled "To Database" in the dialog box that follows. If your BAK file is being used to restore an existing database, enter the name of that database here. Enter a different name to create a new database from your BAK file.
Enter the location of your .bak file. Locate the field labeled "From Device" in the same dialog box. Click the corresponding drop-down menu and select the location of your BAK file. Click "OK." Your SQL Server database has been restored using your BAK file.