How to Recover Btrieve database without FILE.DDF, FIELD.DDF and INDEX.DDF, on Pervasive SQL?

Btrieve developers could use whatever extension they wanted.  These DDF files could also be Btrieve files, but they are not "THE" DDF files that you need for easy SQL-level access.  Try a BUTIL -RECOVER on them as well and see if they contain viable data or not.  They could also be some internal format the developer designed, too, or even just text files.

Obviously, you don't have the data dictionaries for access via SQL, so the original problem still remains -- you'll need to either build them or extract the data from the UNF files.

Thanks for the comment !! Could you please elaborate on which UNF files I can use to extract the data?

Your other post indicated that you could use BUTIL to extraxt data.
 The resulting file is called a UNF file.
Just do the same thing on these files with a command like:
  BUTIL -RECOVER LASER.DDF LASER.UNF

I tried but got following error.......

C:\StanC\BMPC\SYSRES>butil -recover BANKMSTR.DDF BANKMSTR.UNF

Btrieve Maintenance Utility 10.10.125.000
Copyright (C) Pervasive Software Inc. 2008
All Rights Reserved.


BUTIL-71: BUTIL has recovered 0 records so far.

BUTIL-71: BUTIL has recovered 0 records so far.

BUTIL-14: The file that caused the error is BANKMSTR.DDF.
BUTIL-100: MicroKernel error = 30. The file specified is not a MicroKernel file.

BUTIL-9: The command did not complete due to an unrecoverable error.

It was worth a try.  Obviously, these are not Btrieve files.  

Can you view them with Notepad, or with a hex editor like Hex Workshop?

Yes, I can view them with Text editor like notepad or editplus. These files are in simple text format, not in Binary or Hex. here are the contents of BANKMASTER.DDF, one of the DDF file.

*
*    Data Descriptor File for Bankmaster PC
*    --------------------------------------
*
*
MESSAGE   *************************************************
MESSAGE   *                                               *
MESSAGE   *   REL V DDF : \BMPC\SYSRES\BANKSMTR.DDF       *
MESSAGE   *                                               *
MESSAGE   *   NATIVE DATA NO LONGER ENABLED               *
MESSAGE   *                                               *
MESSAGE   *************************************************
*
*
*    NATIVE_DATA ENABLED
*
*
*    Define standard prefixes
*    ------------------------
*
*
*
PREFIX IAM \BMPC\DATA
PREFIX REL \BMPC\DATA
PREFIX SEQ \BMPC\DATA
PREFIX RAW \BMPC\PROGRAMS
*
*
*

Also I have attached the file. For the purpose of attaching file I have appended ".txt" extension. Original name of file is "BANKMASTER.DDF".