If you have set a password to protect a ZIP file but have forgotten it, then you need a tool like ZIP Password Unlocker. The program uses two main cracking methods to discard the password.
The first method is the dictionary attack: you will be able to supply the program with a text file with common words, and the program will attempt to use each one of these words to open the ZIP archive. You can use a file of your own or the built-in dictionary. Moreover, the smart mutation option will enable you to test specific letter combinations partly or completely against the lost password. The mutation count and maximum password length for the smart mutation option can be set as you wish.
The second method is a brute force attack; it relies on specifying a range of letters, numbers, and/or symbols. The program will attempt to generate every possible combination according to the maximum and minimum password length that you specify. You can also add your own prefix, suffix, or a custom fixed text, in case you know parts of your password.
The processing speed of the program depends on your computer's speed and the available resources.