Hi,
First let us know which file has been zipped, is it excel file or access or .pst files..??
There are various password recovery softwares available, which you can buy... Kernel for Password Recovery for Access , Outlook password rceovery , SQL server password recovery , VBA password recovery are some softwares which may prove fruitful to your problem...
The demo version of all the softwares is for
free , which recovers only 2 characters of the password. To get the complete password you'll have to buy the
Full version
...
Good Luck..