How do I unwrite protect a write protected 100 megabite zip drive disk? These disk inadvertently write protected themselves and they are not full.

That feature comes with the software that comes with the drive.

Here's Iomega's instructions for Windows and Mac (halfway down): http://www.iomega.com/support/manuals/zip2a/use_disks.html

Hi,
Any particular Zip Disk you are interested in?
Thanks.

Gosh, it's been so long since I've used a Zip disk, I was not aware that others besides Iomega made them...

Hi,
I could only find one other manufacturer of the 100 megabyte Zip Drives:
http://www.nextag.com/Fuji-ZIP-100MB-PC--zz2339822z0z0z1z~ip_100_diskzB9az2--COMPARE-PRICES-html

Looks like Fuji also makes one.