Get the official 7-Zip software (ensure you download from 7-zip.org to avoid malware, as noted in a Malwarebytes blog ).
Ensure all parts ( .001 , .002 , etc.) are in the same folder. Tiebv 7z 001
Sometimes files are incorrectly named (e.g., .r01 instead of .001 ). Ensure the extensions are sequential and correct. Get the official 7-Zip software (ensure you download