I would like to recommend here SysInfoTools Backup Exec BKF Repair
tool that can recover data from corrupted BKF files which are created by NT-Backup as well as Symantec (VERITAS) Backup Execs. If your BKF files are compress or split into multiple parts, you can try this tool. It will recover data from compressed BKF files and from those files which are split into multiple parts. It has many useful features which will help you performing the recovery from corrupted BKF files with high accuracy.
To read more about this tool, you may visit: www.sysinfotools.com/backup-exec-bkf-repair.html