The Magento contacts page is one of the few views that doesn’t render the breadcrumbs block by default, even if it did, no breadcrumbs links have been set anyway, so nothing would show.
To add breadcrumbs to the contacts page specifically, insert the following code to either your theme’s local.xml or contacts.xml file.
<reference name="breadcrumbs" as="breadcrumbs">
The important thing to note here is specifying the layout handle; in this case: contacts_index_index. If the handle is already being used in the xml file that you are editing, simply copy the from the <reference name=”breadcrumbs” as=”breadcrumbs”> to the closing </reference> part and paste that inside the existing handle.
Remember to clear the Magento cache afterwards.