If one of your .nds roms works and the others roms worked at one point, then they must have gotten corrupt somehow. You should try a different microSD card if you get the same problem after reloading the roms. Also, make sure you format your microSD as FAT and not FAT32 or NTFS.
You might need to reload the other games
If one of your .nds roms works and the others roms worked at one point, then they must have gotten corrupt somehow. You should try a different microSD card if you get the same problem after reloading the roms. Also, make sure you format your microSD as FAT and not FAT32 or NTFS.