Duty Solenoid B
 

!2 power flashes = Duty Solenoid B

Thats what I got when I checked the codes. What should I do to fix this problem or is it time for a rebuild?

And at the moment, my car does not shift into 1st, 2nd, and Reverse. Could the Duty Solenoid B, be the cause of the problem?

Code 12 and shifting are not related.

It's possible one of the clutches (low/reverse) is worn out.