I can open it up in PSP X7 (the program I created it in), but something has gone horribly wrong and it's all messed-up. I can't even go back to a previous save, because every single one of them is messed-up as well.
The preview is tiny, but you can see here (when I browse to open the file) that the axe looks "intact":

However, once I open it up in the workspace, this is the mess I've got:

I've been using PSP (various versions) for over a decade, and I've never seen anything like this happen before. I'm completely stumped as to what caused it, or how to fix it.
I tested another PSD file I had made about a week ago and there's nothing wrong with it. So it just seems to be this file (and all my previous saved versions of it).
I also attempted to open it in the GIMP 2, and got this error message:

GIMP 2 does support Pack Bits compression, and again, I tested one of my other PSD files (also created in PSP X7) in GIMP 2 and it was fine. So... it looks like there's some kind of compression corruption/damage?
I've tried running the file through 3 different PSD repair programs, but have had no luck. Advanced PSD Repair and Remo Repair PSD gave me the exact same results: some layers looked fine, others were a bright neon-pink pixelated mess, and some layers were missing. Yodot PSD Repair had all the layers, but they were all a bright neon-pink pixelated mess, and the whole image was squashed horizontally.
Can anyone help me, please? I spent countless hours working on this, and I just can't start all over again from scratch...
