Backup and Restore SQL server files and filegroups I have a database called Admin. It has only one default filegroup called primary. 

File group: primary
files in the file group: Admin_data.mdf


Now I have taken a full filegroup backup.

Backup file name: fg_full.bak


Then created a new ndf in the same file group called sec_file.ndf and created few tables, inserted 1000 rows on each table.

After an hour took a file backup of my MDF and NDF files

MDF backup: Admin_Data.bak
NDF backup: sec_file_ndf.bak


File Backup using SSMS


Here somehow my sec_file get deleted so I want to restore latest NDF backup, how can I restore it?

Output of restore headeronly 



Restore filelistonly from disk = 'D:\sec_file_ndf.bak'
Query the backup file with 

RESTORE HEADERONLY FROM DISK = 'D:\sec_file_ndf.bak'


and 

RESTORE FILELISTONLY FROM DISK= 'D:\sec_file_ndf.bak' 


...to verify the contents of your D:\sec_file_ndf.bak file. 

You might have multiple backups in one *.BAK file. If so add the option FILE = 2 to your RESTORE command to restore your most recent backup of the *.NDF file.