I mean for luma3ds it self.
for example,if i lost the arm9payload.bin file,how I get it again?
i don't remember creating that file and i found it in the SD card after switching to a9lh.
Luma's arm9loaderhax.bin file is officially distributed in the releases. So for instance if you download Luma3DSv5.5.7z you'll see that the file is in there, you'll just have to copy it to the SD card, make sure that the /luma folder exists and everything should be fine.