Abstract: Due to developing trend for the reliability of software with new and advanced features, reengineering is core demand of this age. For the purpose of assurance of proposal validity, a huge analysis of existing approaches with proper referencing performed and proposed a new generalized model based theory. In this paper, phases of reengineering as core of restructuring and refactoring, reverse and forward engineering is going to be discussed with the objective of quality and user requirements. Restructuring covers the areas as code patterns, object-oriented patterns, an architecture for the extraction of design and restructured documents generated. By the restructure of data, an advanced product with more features can be obtained by passing all steps of forwarding engineering.