One thing that can happen, when using a ZIP is that the file that you thought that you had created on the desktop is actually on the ZIP disk--and the file may actually be there instead of on your hard drive--

Amos would know better, but if your computer seems to be working, I can't see any reason not to try to open the ZIP disk, It hasn't been my experience that that a computer crash destroys files on an external drive--if you want, it might be good to try to read a non-critical disc in the ZIP drive first--

Also, for future reference, it is important to use back-up disks only for back-up