AT3 is a psp audio file format, so I'm not sure what that is for.

What are the .png images of?? That might give us more info.

Once you find the ISO, the only thing you have to do is put it in the ISO folder in the psp root directory, don't worry about other stuff right now.

EDIT:

I did a little looking around, and what you seem to have is a raw umd dump or something. This would require you to rebuild it into an ISO wherein you would be able to remove things like audio etc to shrink down the file. I have no idea how to do that sorry, I've seen some stuff about a program "umdgen", but I have no use for it, so I'm not about to go through the whole process, looks like you'll need someone else to help. If all else fails just find a new copy one that doesn't require rebuilding.

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