There is a tool that can be used to attempt to recover .fbr files that are reported as corrupted, which is available for download here.

To use it:

  1. Make a backup copy of the corrupt FBR file.
  2. Extract the FBRChecker tool and run FBRChecker.exe
  3. Select the corrupt FBR file and click 'Check'
  4. If you see a message saying that the file can be recovered, click 'Recover' and choose a file name for the recovered copy of the file (do not attempt to overwrite corrupt copy of the file).