code: public void undeleteResource(String resourcename, boolean recursive) throws CmsException {
  
          CmsResource resource = readResource(resourcename, CmsResourceFilter.ALL);
          getResourceType(resource).undelete(this, m_securityManager, resource, recursive);
      }
docs: Undeletes a resource.<p>
  
  Only resources that have already been published once can be undeleted,
  if a "new" resource is deleted it can not be undeleted.<p>
  
  @param resourcename the name of the resource to undelete
  @param recursive if this operation is to be applied recursively to all resources in a folder
  
  @throws CmsException if something goes wrong
  
  @see CmsObject#undoChanges(String, CmsResource.CmsResourceUndoMode)