My 1997AWD honda crv came up with check engine light and on checking with obdii it brought out these codes

1. P0700 transmission control system malfunction
2. P0715 input/turbine speed sensor A circuit malfunction.

It used to move and will behave as if it was on one gear for a while and the engine sound will go high.
Now the car does not move again as if in neutral gear and the mechanic said i should buy a new transmission. Is it possible to fix this without buying a new transmission?