[ForumExcellence]

The default style is located in the vBulletin files at:

forumroot/install/vbulletin-style.xml

Go to AdminCP -> Styles & Templates -> Download / Upload Styles -> Either select the file from the vBulletin files on your computer to be uploaded, or, if you still have the install directory on your server, update the second text area (beside "OR import the XML file from your server") with the install directory location, or if you've kept it default, (and this is true for whether you're uploading it or getting it from the server, name the style if you'd like (with the box beside "Title for Uploaded Style"), set its Parent Style, Display Order, and whether members will be able to select it, and then click the "Import" button at the bottom of the page.