Nissan 92 automatic wont go into any gear

What is your question?

I just replace the motor in my Nissan truck and it was driving well I went down to the store when inside came back out and went to put it in reverse and it wouldn't go into any gear it's like it's stuck in neutral you can hear the motor it's running great I'll check the flywheel to torque converter the starter the shifter but can't find what would cause it. Can someone please help

What makes this problem better or worse?

Nothing changes it, it will not go into gear no matter what

How long has your 1992 Nissan 240SX had this problem?

Three days