Reliability on Wireless Sensor Network (WSN) will provide fault tolerant network and find out the failures which are occurred at various levels. The main task of sensor is to monitor the area, by collecting the data and transmit the data to sink node. Fault occurred in sensors due to low cost and limited energy. Reliability requirements and drawbacks are depends on the resources utilized by the WSN. Routing protocols are used to transfers data to the sink node from sensors without error and to provide reliability against sinkhole and node clone attack. In this paper we study the reliability enhancement by routing protocols to transfer a data, a hardware spare that replaces sensors when failed and modeling reliability in WSN and compare the performance also.