Recently, tagging systems are widely used on the Internet. On desktops, tags are also supported by some semantic file systems and desktop search tools. In this paper, we focus on personal tag organization to enhance personal file retrieval. Our approach is based on the notion of context. A context is a set of tags assigned to a file by a user. Based on tag popularity and relationships between tags, our proposed algorithm creates a hierarchy of contexts on which a user can navigate to retrieve files in an effective manner.