Fcrackzip is a small utility that can become a handy tool when you want to look for lost zip password.
Fcracksip i a available in the ubuntu repository and you can install it as
$ sudo apt-get install fcrackzip
To see the available options with fcrackzip , try the following.
$ fcrackzip --help
You can look for a password like this.
$ fcrackzip -c a -p aaaaaa sample.zip
The above cimmand will check the encrypted files in sample.zip for all lowercase 6 character passwords (aaaaaa ... abaaba ... ghfgrg ... zzzzzz).
fcrackzip supports brute force mode as well as dictionary mode. The man page has some more interesting options you can try.