In this study, we developed a discrete theory of the charge transport in thin dielectric films by trapped electrons or holes, that is applicable both for the case of countable and a large number of traps. It was shown that Shockley-Read-Hall-like transport equations, which describe 1D transport through dielectric layers, might incorrectly describe the charge flow through the ultra-thin layers with a countable number of traps, taking into account injection-from and extraction-to electrodes (contacts). A comparison with other theoretical models shows a good agreement. The developed model can be applied to one-, two- and three-dimensional systems. The model, formulated in a system of linear algebraic equations, can be implemented in the computational code using different optimized libraries. We demonstrated that analytical solutions can be found for stationary cases for any trap distribution and for dynamics of system evolution for special cases. These solutions can be used to test the code and for studying of charge transport properties of thin dielectric films.