Non linear systems of equations (Convergence).

Question

I am an engineering student and I don't have any mathematical background in iterative methods. I am trying to solve a non-linear system of 14 equations and 14 unknowns as part of a project. I tried solving the system using both Jacobi and Gauss-Seidel methods. However, I have failed to obtain convergence in both cases. I would be grateful if someone could give some insight on how to approach such a problem.