I would like to take MSSQL server db backup. Is there any plugin available for it.
I don't know of any current plugins for doing this. That may because a lot of backup functionality is built into MSSQL.
The easiest way to automate a backup via Jenkins may be to use a command line script to use a sql command:
Sqlcmd -E -S touch -Q" BACKUP DATABASE [DBName] TO DISK = 'C:\artifact_directory\my_db_backup.BAK'
You could also also avoid automating this via Jenkins and just create a scheduled backup directly within SQL Server.