If the archive is corrupt, try using the "Repair" function in WinRAR or redownloading only that specific part. Corrupt RAR file on almost all files - SABnzbd Forums
If you get an error specifically for part04.rar , ensure the file is in the same folder as all other parts and has the exact same naming convention. Download Patch part04 rar
Use a tool like 7-Zip or WinRAR. Right-click Part 01 and select "Extract Here." The software will automatically pull data from all subsequent parts (including part 04) to recreate the original file. If the archive is corrupt, try using the
Ensure you have downloaded every part (part01, part02, part03, etc.) before attempting to extract. If any part is missing, the extraction will fail. Right-click Part 01 and select "Extract Here
Check that all parts (except the final one) are the same size. A different size often indicates a corrupt download that needs to be redownloaded.