Will changing the PWM is the same as changing the C solenoid?

Question

P0762 code, scanner recommended changing the trans oil and filter. Before changing the oil and filter, it'll shift, sometimes until the fourth gear, sometimes until the second, and the reverse worked after shifting it back and forth for maybe 20-30 times. After the oil-filter change, now the reverse engages just fine, but will not engage forward. Yes, the check engine was on before the AT light went on. I have reset the circuit a few times. In the beginning it would work, but after a few minutes the check engine light will light back on. That's about my life story.