This paper presents an information retrieval methodology which uses Formal Concept Analysis in conjunction with semantics to provide contextual answers to users' queries. User formulates a query on a set of heterogeneous data sources. This set is semantically unified by the proposed notion conceptual context. A context can be global: it defines a semantic space the user can query - or instantaneous- it defines the current position of the user in the semantic space. Our methodology consists first in a pre-treatment providing the global conceptual context and then in an online contextual processing of users' requests, associated to an instantaneous context This methodology can be applied to heterogeneous data sources such as web pages, databases, email, personal documents and images, etc. One interest of our approach is to perform a more relevant and refined information retrieval and contextual navigation, closer to the users' expectation.