Find your registration templates by clicking on "Modify" under the "Templates" header in the sidebar of your Admin Control Panel...
Expand the template set(s) you wish to revert the registration template(s) for, then scroll down and expand the "Registration Templates" header...
If your templates have been edited, they will appear as a blue colour (providing you use the Default vB .css file) - Beside the blue name, there will be 3 links, saying "[edit]", "[revert to original]", "[view original]"...
Click on "[revert to original]", then click "yes" on the confirm screen...
Your image registration confirmation should be active
If it is not, edit the vBulletin Options screen, and set the "Image on Registration" setting to yes
Satan