Trouble with Yamaha 150 outboard

[SkunkBoat]

Hub not likely because yuo can go fwd but that can be checked with motor not running. Shift gears and spin prop by hand. Figure out if gear is shifting but prop spinning.

remove cowling and see whats happening when you shift. try to shift from there.
Get a sense of if it is shifting but not working or not really getting from N to R.

The linkage might have slipped or the rod down to the lower unit bent?

Another step would be drop lower unit and see if you can shift it.