In version 2.0 we changed the behaviour of the Settings page to no longer display anything when jQuery fails as a lot of the elements on the settings page are dependent on jQuery functioning properly (otherwise a lot of unexpected behaviour can occur). We also added functionally that relies on the jQuery UI library version included with WordPress 3.5. As such, Mantra’s 2.0 settings page will to work on older WordPress versions.
If you are using WordPress older than 3.5, please update to the latest version. If you cannot update, use Mantra 188.8.131.52.
Another way is to disable all your installed plugins (this should make the settings page functional again) and then re-enable them one by one until Mantra’s Settings page fails to work again to see which plugin is the issue.