FBK is a backup file associated with Microsoft Dynamics NAV. FBK files store backup copies of FDB database files. Microsoft Dynamics NAV uses ODBC protocol for accessing database records, so before creating FBK files all active session must be stopped.
After converting the file to the new format, you will be able to use other programs to support it. Keep in mind, however, that the FTW file after converting to FBK may differ slightly from the original. The most important information should be kept, but if you want the file after conversion from FTW to FBK to be the same, you have to do this carefully and choose the proper application from the list below.
There is no guarantee, of course, that the conversion will come up to all your expectations, but it will certainly help you. If, after all, the effect of converting FTW to FBK does not meet your expectations, you can simply try to find on the Internet a different version of your file in FTW format, properly converted to a FBK file by someone else. If this fails, use the information provided in the further part of the website.
Unfortunately, if after performing the two previously described steps (trying to find your FTW file converted by someone else, and the attempt to convert it to FBK on your own) you still have a problem with your file, then there are only a few solutions left. You can once again try to find and install an application that can open the FTW file in its original format (without conversion to FBK file). Such a solution will be difficult to implement, but it certainly will give the best result.