old and busted

[nazgulnarsil]

 

[deepceleron]

7zip encryption is strong and slow AES256 with password stretching. Good lucks:

http://www.crark.net/crark-7zip.html

[BookLover]

You can try fcrackzip but I'm not sure if it will work on 7zip.

[Martijnvdc]

use rarcrack... it's quite popular

[Qbeczeq]

Try search programs for bruteforce method. But there's question now, if your password cointains words only