Don't Know What It This.part3.rar -

: This file is not a standalone archive. To extract the contents, you must have all other parts (e.g., part1.rar , part2.rar , etc.) in the same folder.

Do you have the of this archive, or are you trying to repair a broken download? Don't Know What It This.part3.rar

: Ensure you have part1 through the final numbered part saved in one location. : This file is not a standalone archive