HELP! What happend?
 

Your Notifications: 1 < no dropdown, no nothing....It used to work just fine...now it doesn't? How do I fix it?

Clear your cache and cookies, then try again. ;)

my computer cache and cookies, I did that...Nothing...

Ctrl-F5 ?

Nothing, its like the javascript isn't working or something...No drop down from the little arrow...Clicking the Your Notifications link does nothing either...It shows the usercp address but does nothing when clicked.

Create a new style with no parent:

• Styles & Templates > Style Manager > Add New Style
• Parent Style: No Parent Style
• Title: Default vBulletin
• Allow User Selection: Yes
• Save

Then browse the site using that totally default vbulletin style - do you still have the same problem?

If it is still happening - Try disabling your modifications/plugins and see if you still have this problem.
Note: To temporarily disable the plugin system, edit config.php and add this line right under <?php

Don't forget that for vbseo, disabling the modification means to also get rid of anything extra you added to your htaccess file.