Wireless Sensor Networks (WSN) are a heterogeneous system with a collection of sensors distributed unbalanced patterns in remote areas, and often in unfriendly environments, without any pre-deployed architecture, and with limited hardware inside them. As the use of wireless sensor networks continuously growing, it should require efficient security mechanisms. Therefore to ensure the security of communication and data access control in WSN plays a vital role and has top significance. Because sensor networks may interact with sensitive data and operate in hostile unattended environments, it is necessary that these security issues should be addressed from the beginning of design of the system itself. In this paper we are presenting secure network protocol and security mechanism for Data Access Control which is built upon network layer of WSNs and our focus is on data access control and secure network protocol. Here Virtual Counter Manager (VCM) along with the synchronized incremental counter is presented for detection of replay and jamming attack using basis of symmetric key cryptosystem. For access control & prevention from unauthorized access we are presenting Key-Lock Matching (KLM) method.