If one part is missing or partially downloaded, the extraction will fail. Re-download the specific part that is corrupted.

Files named name.part1.rar , name.part2.rar , etc., are interdependent.

You cannot simply open part1 to get all the data. You must have all parts ( part1 , part2 , part3 , etc.) in the same folder, and the software will merge them during extraction.