Try using BKF Repair Software as it is easy to use and fast BKF files Recovery Software and involve only few simple steps to recover bkf files/data as follows:

Step.1:  Open BKF Repair that you have download(demo/full version)

Go to Start » Programs » BKF Repair. Open BKF Repair, start-up screen appear as follows:

Load corrupt/damaged BKF files:
Click on Load button, to open & load corrupt BKF files.Then, this will take you to the browsing option as shown below:

Step.2: Select the corrupt BKF file that you want to repair

After selecting click the "Open" button.
BKF Repair reads bkf file & displays files and folders after completely loading BKF file. Then software start loading process to load the selected BKF file as shown below:

Step.3: Search Files within BKF File

After loading process completes, software displays the following screen:

(You can search for particular files, images, pictures using Search from the top of the screen. )

Step.4: Extract Files from BKF File:

After this, click Extract button to save or Extract Files the files & folders from corrupt BKF files.As you click on Extract button software will ask you to locate the location that you want to save the files as shown below:

Follow these four simple you can easily recover you bkf files using BKF Repair Software. Still if you have any queries; contact the technical support team which is available 24X7 for your help. You can either do online chat or send email to support@group.com

After saving files and folders you can open other BKF files.

How to Load another BKF file? To Repair any other corrupt BKF files, you need not to start from the start up screen.

Choose an other BKF file:
Choose the BKF file from the left tree structure, right click and choose the Close Backup File option:

Now software closes the backup file. Click Load button to load another file that you want to recover.
Partial Scan:
You can quickly do partial scan if you want to extract only a small portion of data from any large sized BKF file. It is new feature of updated version (5.1) of BKF Repair tool
If you want to recover only few files then click on the “Actions” menu and select "Partial Scan" option from thedown menu as shown below

: 
As you click on the Partial Scan option, you will see the following window:  

Enter a value (the percentage of data that will be extracted from the selected large sized BKF files that you want to scan) in the above window.
(For example – if you enter the value as “25”, then the software will recover 25% of data from the selected BKF file.)
Privew the Selected BKF files:
After Partial Scan completes, you can preview the selected files as shown below:

In short the use of BKF Repair software is very easy. You can download the Demo version of it to try. The Demo version is completely FREE!. But Demo version has some limitations.