Starting with SQL Server 2005, your SQL Server instance includes a read-only hidden database that contains all the system objects. The mssqlsystemresource.mdf and mssqlsystemresource.ldf files are located in C:\Program Files\Microsoft SQL Server\MSSQL11.\MSSQL\Binn\ as the default location. The important thing to remember is this “hidden” database is required by the master database, and if it is lost it will cause serious issues. Since it is a hidden database SQL Server also won’t show it as a database available as part of your standard database maintenance plan.
As stated by Microsoft, you need to manually backup and restore these files outside of SQL Server. This is usually as simple as using your tape backup software to pick up the files to tape, or by using xcopy to duplicate the files to a backup location.