: If part 12 is the last one you have but the program asks for "part 13," you are missing a file.
The file "Final.Fantasy.XIII.part12.rar" is part of a , meaning it is just one piece of a larger set required to extract the full game or content. How to Extract Multi-Part RAR Files Final.Fantasy.XIII.part12.rar
If you are actually looking for a guide to of the game (Eden), here are key strategies from expert walkthroughs on IGN and GameFAQs : : If part 12 is the last one
: Do not rename the files. They must have identical names except for the part numbers. Final.Fantasy.XIII.part12.rar