I'm afraid that if you don't have some earlier version(s) saved, it
may not be possible to fix this--though maybe someone here knows how...

One "silent" way of making a .ps3 file unusable is to add enough to
it to cause it to go over some magic amount of memory required--at which
point it cannot proceed.

Since there is no warning that this point is being approached, I save
any "largish" .ps3 file with rotating version names so I have some
recourse if/when I hit the wall.

I know this may be little consolation if you have lost your work, but
it can save you this problem in the future--as would fixing Photo Story
so that it handled large files more gracefully (hint, hint)!

BTW, if you now attempt to re-create your show from scratch, you may
be surprised how much more quickly you can get to your desired result
than it took the first time.  Losing your work can be an opportunity
in disguise, since you can now proceed to do exactly what you now
know you want--often more directly and with better results.

-michael

"The wastebasket is our most important design
tool--and it's seriously underused."