How to crack a password protected zip file
This is reputed to be the gold standard in archive extractors. Not particularly cheap, but they have a great reputation. Elcomsoft Advanced Archive Password Recovery.
The assumption I'm making here is that it's the archive which has the password. This is based on the fact that you say it cannot be extracted; if it were the .exe which were password protected you could extract it, you just wouldn't be able to act on the .exe. Secondly, programs inside password-protected archives are very common, and password protected .exe's are less so.