Ok the path of the files on the server will have changed.
In your /gallery/gallery_config.php
$forumpath = '/path/to/your/forums';
Also make sure you enable read/write access to the folder where your images and other media are located. Default: /gallery/files/
Next log-in to In the AdminCP of vBulletin.
AdminCP => vBGallery => Modify Settings
- Title, URL's, & Paths
Here you can update the gallery settings.