If you only have .part1.rar and are missing the other parts, the extraction will fail. Ensure you have downloaded the entire archive set. To help you further, could you tell me: Where did you download this file from? Are you seeing an error message when trying to extract it? Do you have the other parts (part2, part3, etc.)?
Knowing these details will allow me to provide specific instructions. Npri_alpha045.part1.rar
Ensure you have Npri_alpha045.part1.rar , Npri_alpha045.part2.rar , etc., in the same directory. If you only have
Use tools like WinRAR, 7-Zip , or The Unarchiver (for Mac). Npri_alpha045.part1.rar
Right-click only on the .part1.rar file and select "Extract Here" or "Extract to...".