how do you replace oil pump?

If changing the oil pump is needed I will attach the process below. However, if you are not getting oil through the engine then you are most likely correct but have you checked the pressure to be sure the pump is not creating pressure but you just have a restriction preventing oil from getting to where you are checking it?

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

Please see the info below on how to check the oil pressure and replacing the pump and removing the oil pan which is needed in order to get this completed.

Please run through this material and let us know if you have other questions. Thanks