Convert what into a Messenger Plus Script pack?
If you've created a Zip file and want to turn it into a script you just need to rename it from .zip to .plsc.
The zip will be showing as empty if Norton cleans it out on download.
Disable Norton, clear your internet cache and then re-download it, or use one the mirror here:
http://rnd.menthix.net/mpl_mirror/extras/