Load Category in Plugin
Depending on what you are searching by, you can use something similar to this. You can see the properties you can search by in the documentation.

$criteria = craft()-&gt;elements-&gt;getCriteria(ElementType::Category);
$criteria-&gt;group = 'CategoryGroupName';
$criteria-&gt;title = 'CategoryTitle';
$criteria-&gt;limit = 1;

$category = $criteria-&gt;find();