If you have any kind of backup arranged for your machine, see about restoring the file. If you don't have any kind of backup, then for the future make it a practice to save older versions as backup on a somewhat regular basis.
When you start editing files try to make it a habit to save new copies rather than sacving over older files.
When you have files that involve customers, value, or extensive effort, you should keep multiple copies on different media/storage devices. Every so often I save files and whatnot to dvd data disks.
As far as recovering the file that keeps crashing, try entering some terms like "restore corrupted file" in the top of the forum where it says Ask a Question and see if any results come up that lead to some help. I remember someone recently talking about renaming files or some such thing and opening them, though you'd need to find it to try it properly.
if you have a working swf, you can decompile it and reconstitute your fla.
in any case, you should save your fla periodically with different names like yourfla_01.fla, yourfla_02.fla etc so you never risk loosing too much work.
Thankfully I did create backups and had earlier versions of the files. After a couple hours of work I've reconstructed most of the corrupted .fla file.
Still quite frustrating though. Oh well, I guess it happens. =\
Please go throw the below article and check whether this would resolve your issue.