Due to some strange issue with a computer at work here, a FLA file was corrupted for some strange reason and we couldn’t open it. A little googling to check details on the FLA and XFL format reveals that the FLA file can be unzipped, and with some luck, most of the data can be recovered. Here’s how:
1) Rename the file extension of the FLA file to ZIP
2) Use Windows Explorer to unzip the file to a folder – as of time of this writing, 7-Zip 9.20 cannot open or unzip the file, so its best to stick with Windows Explorer (at least on Windows 7 anyway)
3) ZIP the folder and rename as a FLA file
4) Open in Flash CS5.5, and check your work. If its all OK (or most of the stuff that can be recovered is shown), re-save as a new file
5) Always, always, backup!
UPDATE 13 Nov 2012: It seems that the Flash CS6 has changed its ZIP header files, resulting in extraction errors! If the above method doesn’t work, you can try DiskInternals ZIP Repair