The beauty of .RAR files is that the uploader can add a recovery record to their archive and not have to worry if the server later corrupts the file. This is a brief tutorial of what to do when you come across corrupt .RARs, unfortunately corrupt .ZIPs are useless.
Download all parts of the achive, Right Click on part1 and click Open
In WinRar go to Command then click View Files
Highlight the entire archive, just the archive files, Go to Tools and click Repair Archive.