This work focuses on the effectiveness of using four-wave mixing (FWM) in restoring the corrupted signal as well as the factors that affect the quality of the data. The method was based on the two-stage FWM-based optical wavelength converter designed using a OptiSystem version 18.0. The signal regeneration for both stages has taken place in the highly nonlinear fiber (HNLF) having length of 1.0 km and 0.8 km respectively. The first stage is to convert and restore a signal carrying NRZ formatted data at 1552 nm into a new wavelength of 1548 nm. While the second stage is to transfer the data back into the original wavelength of 1552 nm. It has been found that the quality of the data (Q-factor) is affected by the power of modulated signal (1552 nm) as well as the power of unmodulated pump source (1550 nm). The maximum Q-factor of 29.6 at 6 dBm signal power and of 35.7 at 16 dBm pump power have been achieved here. The wavelength spacing between those two sources also affect the quality of regenerated signal. The optimum quality value is found to be above 25 when the spacing is 1 nm regardless of the signal and pump power values.