You can't open that?
Ok, lets try this :
Download winzip. Open the file with winzip, or open it from winzip.
Extract that file somewhere. Now, I guess it's ISO file when beeing extracted, so use Daemon tools on that one, and mount the .ISO / image file.
If this don't work I would either guess, as mentioned before, that it were password protected.
If nothing of this work it seems that the archive is dead. You could use the program called Winrar, and scan the archive for errors, and see what it tells.
Any information that is rellevant is good, because now it's kind of hard to see the problem. You got this .zip file that you can't open? Write the exact error messages you get.