your mower could have one of several different kinda of transmissions so we really need a bit of help here
For for starters does it have a 6,5,4,3,2,1,N,R shift ?
or
A 1,2,3,4,5, 6 on one stick and F-N-R on another ?
Some pictures would be really helpful
There should be a sticker under the seat with a model number similar to this if it is a ride on from 1998
It should look like 13am667f123
If it was 1993 to 1997 then the model number looks like this 137m 667 f 123
What it can not be is just 667
As for "not go into gears"
does the shifter move as per normal but nothing happens or dose the shifter not move at all ?