Have you installed WinZip to your computer in the past, and then perhaps uninstalled it? It may have taken over the association for this file type. Windows from XP and later has support for zip files built-in; you should be able to right-click on the file/folder and choose "extract". If you have a different archive program, try right-clicking and choosing "Open with..." and choosing the program.

It might be an idea to download a free utility such as 7-zip to take the place of Winzip. When installing, make sure it is associated with zip files.