Попробуй Advanced RAR Repair
RAR.Repair.Advanced.RAR.Repair.v1.0.Retail-ZWT.zip 555.43 KB
Он как раз предназначен для подобных целей.
Advanced RAR Repair (ARAR) is a powerful tool to repair corrupt or damaged RAR files. It uses advanced technologies to scan the corrupt or damaged archives and recover your files in them as much as possible, so to minimize the loss in file corruption.