Is there any simple & freeware program to fix corrupted zip files for windows platform ? I've lot of corrupted zip files and would like to recover some of the files from it
WinRar repairs damaged archives.
WinRar is shareware, but available as an unlimited trial (if you don't register and pay, the program simply "nags", it doesn't stop working).
There's also DiskInternals ZIP Repair
I have no idea if it is available on windows, but you did ask for an open source answer (that's probably available under cygwin though).
You might use the zip command itself (at least under linux):
If only some bits are missing (incomplete download):
If the archive's data is damaged (wrong data) (this command is less reliable):