: Ensure you have every single numbered part in the same folder (e.g., filename.part01.rar , filename.part02.rar ... through to your .r21 and beyond).
Here is everything you need to know about what an .r21 file is and how to properly open it. What is an .R21 File?
Splitting archives was common for fitting data onto multiple CDs or DVDs, but it is still used today to:
: The software will automatically look for .r01 , .r02 , and your .r21 file to piece the original data back together. Common Issues
: Right-click the first file and select "Extract Here" or "Extract to [Folder Name]."