Text summarization is the process of creating a short, accurate and fluent summary of a longer text document. As plenty of digital data is available online, automatic text summarization methods greatly needed to help and understand the lengthy & complex documents quickly by discovering the relevant information. This paper proposes the text summarization method for short news articles and long scientific papers using unsupervised neural network model. The proposed method works in four main steps: input document preprocessing, feature extraction, feature enhancement and final summary generation. We have extracted combination of various statistical and linguistic features from input document, which helps in improving the quality of sentence selection. Further Restricted Boltzmann Machine (RBM) model is used to capture & enhance the discriminative, abstract features in an unsupervised way to improve the overall performance without losing any significant information. Sentences are scored based on enhanced feature set and top sentences are selected for final extractive summary. Performance of the proposed method is evaluated using Rouge score and compared with TextRank, LexRank, LSA & Luhn baseline methods and the results demonstrates that proposed methodology performs better compared to other methods.