When the process of retrieval for concepts fails receptively, we may find that familiar referents are now unrecognizable to us--AGNOSIA
When this process fails, and we are unable to retrieve concepts for things we see or hear, they become unrecognizable to us.
This condition, which is receptive, is referred to as Agnosia.
It may be total, in which case the patients may seem deaf or blind, although their ears and eyes are functional. It may be partial. For example patients mayrecognize utensils as eating implements but not be able to discriminate between a fork and a spoon.
On the expressive side, is the process of retrieving information (concepts) to formulate a thought or an idea worth communicating.
When this process fails, one can experience an inability to think.
NOTES: Here is a more detailed description of agnosia.